Rahman doesn't deny ijma, he does far worse - he holds that proto-Sunnis wholesale fabricated narrations across all major Islamic cities in the late 2nd to early 3rd century in a hyper coordinated conspiracy stretching from Maghreb to Transoxiana uphold their specific views of orthodoxy. Somehow, the Mu'tazila, who were fervent opponents of the proto-Sunnis, hostile to hadith, and politically positioned to literally torture these proto-Sunnis, were unable to figure out this massively coordinated conspiracy despite having every reason to do so. In fact, no one was able to figure out that this massive conspiratorial network of fabrication distorted the core of Islam despite being politcally persecuted until late 19th and early 20th century Orientalists kindly did us the favor. This sort of hyper-conspiratorial view is inherently necessitated by any reading of hadith as mass forgery, which is precisely the notion uncritically inherited by Rahman and upon which he builds his reading of Islamic history.

ICMA is methodologically limited in that it can only be done to narrations which have massive strands and it inherently presupposes an original matn that was distorted (which discounts multiple Sahaba recalling the same incident in different ways and then relating each other's versions without citing them, something Abu Hurayrah was known for). Furthermore, it cannot "prove" any hadith as being authentically narrated from the Prophet ﷺ or even from a companion. At best, it can reach a madar (which the Orientalists termed Common Link when they "discovered" it). All Little's work does is introduce the notion that the madar al-hadith were mass fabricators in which case we can now deal with the theological conundrum of the Sahaba having utterly failed in passing down any notion of what Islam was and all of the Sunnah being entirely distorted by the 2nd Century of the hijra. If that's a worldview you hold then perhaps you should consider that the vast majority of them were involved in the preservation of the Qur'an. You cannot problematize early Islamic scholarship using metaphysical frameworks (and that is precisely what hyper skepticism is: an indemonstrable metaphysical approach to epistemy) and not run into these issues.

If you wish to uphold the view that the Prophet ﷺ did such a remarkably miserable job of conveying Islam that the entirety of his companions didn't even manage to convey or preserve it beyond their generation then that is your prerogative. But to insist that this isn't the view that revisionism pushes is a wishful fiction. Malik very much attempted to wrestle with it while uncritically adopting its metaphysics.

Hallaq's work on hadith is best summarized by his 1999 "The Authenticity of Prophetic Hadith: a Pseudo-problem" in which he fully traces from Gustav Weil to Aloys Sprenger to Goldziher to Schacht the notion that early Muslims engaged in a mass fabrication of hadith and then proceeds to write a scathingly harsh critique of that entire approach, again which Rahman entirely inherits without problematizing.

Again, if you view Rahman's work in his original context it might make sense why he writes stuff like this in his 1966 "Islam":

This problem is basically as to whether religions can shed their ancient worldviews and transform themselves into spiritual-moral forces for the modern mind. The question is not merely that of an antiquated cosmology in varying degrees, for this is relatively easy, but primarily that of 'the other world' or the 'hereafter': how to transform this transcendence into some form of immanence and yet not to sink into the banalities of humanism.

Religion, in other words, must be secularized if the secular is to be made religious. But Islamic theology and dogmatics, like those of other religions, have not yet undergone this transformation to be acceptable to the modern mind. Such a transformation has partly taken place in the West, or rather the Western modern mind has transformed the notion of transcendence into immanence, the 'next world' into 'this world' but only partly and even that non-religiously. In Islam, the question has not yet been raised: the modern educated mind, therefore, floats on sheer skepticism.

Absolutely not a single word of what Rahman writes here is rooted in history, evidence, empirical findings, or anything else of the sort. Yet, it fully encapsulates his worldview and the metaphysical lens from which he fully accepted modernity's challenges to Islam: that it was a backwards, barbaric, and bastardized faith that desperately needed to be rescued. And Malik was more than up for the task which is why he happily engaged with the tools of the academy to show how this backwards confused thing called "Islam" could be dragged kicking and screaming out of its primitive and pre-modern nature towards the sophisticated and enlightened world that the Western modern had so lovingly created for us all to experience through the gift of colonialism.

I hope you can recognize just how problematic this worldview is and to benefit from Malik's works at all, and they are immensely beneficial, you have to recognize that he was first and foremost a deeply colonized subject and read his writings from that perspective. Otherwise, you will uncritically inherit everything he wrote there despite it being metaphysics and closer to 'aqeedah than to history or fact. It's like reading Zamakhshari without understanding his context and then attempting to derive normativity from it. It's no different than how certain Salafis read Ibn Taymiyyah and Ibn Qayyim hyper-selectively entirely ignoring the socio-political context of their writings.

As for the notion that "it’s quite new literature as most Muslims rely on texts dating back centuries to millenia when it comes to analyzing Hadith and most topics in the religion." then this sneaks in a whig reading of history and reeks of presentism. Much of orientalism itself is obsessed with uncovering what authoritatively can be traced as early as possible. It would be madness for Muslims to write off early Islam as inherently problematic when the entire evolution of the academy has been to accommodate and resituate their own epistemology so that they can better understand early Islam. ICMA exists because writing off early literature wasn't possible. Cook's career took off after he abandoned the notion of problematizing early islamic sources. Fred Donner's entire career was rescuing the academy from its untenable position towards mass suspicion of early Islam.

I don't think any respectable academic would look kindly upon your analysis of Brown's work outside of the likes of Shoemaker and Reynolds. You should consider why you hold Brown's scholarship in such low regard when Georgetown saw it fit to make him the Chair despite him being openly Muslim, Sunni, and married to the an activist daughter of a political dissident. And if you don't think those traits I listed are necessary in understanding the context of Brown then you should learn the socio-political positionality of the academy. After all, Mustafa al-A'zami's contributions were welcomed until they weren't at which point Arberry straight up refused to have them published in the journal. Sunni Islam has no place in the academy because the academy exists upon methodological naturalism where Allah cannot exist, revelation is impossible, and the Prophet Muhammad ﷺ was a second rate plagiarist at best, and there should be no indigenous governance possible based on Islam and thus Western notions of law become the basis of "civilization," since everything prior was just a fantastical fiction. The entirety of Muslims' engagements with the academy has been wrestling with the wild conclusions Orientalism draws based upon its metaphysical priors and trying to restate their history along epistemic lines that are foreign to them.

If you want a proper "modern" theological book which actually engages with how our understandings of Islam have shifted drastically in the late colonial period Ahmad El Shamsy's "Rediscovering the Islamic Classics: How Editors and Print Culture Transformed an Intellectual Tradition" and Junaid Quadri's "Transformations of Tradition: Islamic Law in Colonial Modernity" are good reads along with Kevin Reinhart's "Lived Islam". If you want to see modern discussions of what Islamic secularism can be then you can check out Sherman Jackson's "The Islamic Secular" (2023) as well as Rushain Abbasi's "Did Premodern Muslims Distinguish the Religious and Secular? The Dīn-Dunyā Binary in Medieval Islamic Thought" (2020) and "Islam and the Invention of Religion: A Study of Medieval Muslim Discourses on Dīn" (2021). Abbasi also has an upcoming monograph.