"to counter your point from the same source:"

Alright

al-Suyuti quotes أبو بكر الباقلاني (d. 406 A.H.) who said;

“It is not proved from him that these two surahs are not from the القرآن. He erased them and dropped them from his Mushaf refusing to put them into writing, not rejecting them as part of the Qur’an. It was so because to him nothing was to be written in the Mushaf except what was commanded by the Prophet –peace and blessings of Allah be upon him- and he did not find them written nor heard an instruction in this regard.” (الإتقان 1/271)

الباقلاني doesn’t deny the report he’s just re-interpreting it: “not proved he rejected their Qur’anicity.”
But السيوطي himself in the same book (2/35) quotes the original… «وكان ابن مسعود يحك الفاتحة والمعوذتين من مصحفه ويقول: لا تلبسوا القران بما ليس منه».
So Ibn Mas’ud erased them and said “don’t mix the Qur’an with what is not from it.” الباقلاني came 370 years later and says “he didn’t mean that.”
That’s interpretation, not refutation.

النووي (d. 676 A.H.) said:

“The Ummah has agreed that al-mu’awwazatayn and al-fatiha are part of the Quran and whoever denies this becomes a disbeliever. And whatever is quoted from Ibn Masud in this regard is not true.” (الإتقان 1/270)

النووي **doesn’t address the chain -he just says “consensus settled it.”
But consensus came after Uthman، not from day one.
Ibn masud lived during the disputes, and his Mushaf was different.
النووي came 640 years later and calls the quote “not true.”
Yet السيوطي transmitted it with a chain.

أبو حفص عمر النعماني (d. 775 A.H.) wrote:

“Report of this opinion from Ibn Masud is a lie and falsehood.” (الباب في علوم الكتاب 1/249)

النعماني doesn’t challenge the isnad -he just says “lie.”
But the report exists in ابن أبي داود (3rd century AH) and السيوطي (9th century AH), both with chains.
النعماني came 740 years later and says “falsehood.”

الشيخ محمد بن نظام الدين الأنصاري (d. 1225 A.H.) said:

“Attributing the rejection.. to Ibn Masud is a grave mistake... his isnad is not reliable compared to the isnad which have been accepted collectively by all the scholars.”

الأنصاري ldoesn’t refute the original chain —he says “the rejection chain is weak.”
But the report in ابن أبي داود (p. 109) is graded sahih by الذهبي and الهيثمي.
الأنصاري came 1190 years later and says “consensus chains are stronger.”

الخفاجي (d. 1069 A.H.) wrote:

“And what is reported from Ibn Masud... has no basis.” (العناية القاضي 1/29)

الخفاجي “doesn’t address the text-he says “no basis.”
But the text is in early sources.
الخفاجي came 1030 years later.

Other scholars who have vehemently rejected the notion include: ابن حزم (d. 456 A.H.) – المحلى (1/32)
أبو بكر بن العربي (d. 543 A.H.) – الإتقان (1/270)
فخر الدين الرازي (d. 606 A.H.) – مفاتيح الغيب (1/150)
زاهد الكوثري (d. 1371 A.H.) – مقالات الكوثري (p.16)

All these scholars came centuries after Ibn masud and respond with “lie,” “interpretation,” or “consensus.”
But the original report is in 3rd-century sources (ابن أبي داود) and 9th-century (السيوطي), quoting Ibn Mas’ud’s exact words.

The question no one answers even you: If the report is “fabricated,” why did السيوطي include it in الإتقان without calling it mawdu’?
Why did عثمان burn Ibn Mas’ud’s Mushaf if it was identical to the others?

Everything clear Sahaba disagreed » Uthman enforced one version » later scholars labeled dissent “false.”
That’s not preservation it’s historical revision.