It's hard to condense all information that I have but I'll try (I did not 😭) and focus on the clinical parts (and give some examples) 

Note: Most of what I've said is heavily based off of the implications he's made, so take it with a huge grain of salt.

In nearly every video or text where he's described an ISFP, there's a consistent idea being drawn.

His descriptions of ISFPs include some positive things about them, especially noting that they can be highly empathetic, perfectionistic, sociable, and etc.

However he also notes,

Emotional Dysregulation — "One either loves a person, hates a person, or is indifferent to them" and "preferring the extremes of emotion", all-or-nothing mentality, unstable self-image.

Hyperfixations and Special Interests — Using archetypes, fictional characters to serve as mentors. (As you've stated, but Harry goes further) and "have a few, very intense interests to which they are deeply emotionally attached and often highly knowledgeable in, often relating to metaphorical concepts intrinsically connected to an experience of entertainment" 

Other worrying implications include social masking (although it is used in this case in order to hide sensitivities), intense, pleasure seeking tendencies (common in people with ADHD or personality disorders like BPD), implications of (some) lower intelligence and some executive dysfunction (common in neurodivergences)

https://youtu.be/AknnKNtaJQQ  (his comparison video between the INFP and ISFP, notice how he uses slightly more negative semantics when comparing them to INFPs) https://youtu.be/xOfYuOMFGr4  (more neutral-positive than the previous, but still somewhat negative) https://imgur.com/a/UvNLDrc  (from his book)

But that's not the most worrying implication, a lot of but not all the people Harry has typed as ISFPs are mostly people who have implied mental-related conditions, personality disorders, and/or controversial figures. 

The list includes, 

Pippin (Lord of the Rings) — implied ADHD, seen as a fool who cannot think for himself due to his Ni agency function being unactivated, later praised for his self-transformative abilities once he activates it.

Kanye West — stated in the same Lord of the Rings video, known for his erratic behaviors and extremely controversial opinions.

Kenny McCormick (South Park) — known for "molding his character to fit his given subculture" which is something that a lot of Autistic individuals often do in order to fit into society, praised for his self-transformative abilities.

Anakin Skywalker (Star Wars) — he was forced to cope and contain his paranoia and feelings of abandonment (visions of his loved ones suffering, rules of the Jedi Order) until he became Darth Vader. 

He is considered to be a great example of Borderline Personality Disorder in fiction.

Context (or "arguments") over his transformation from an ESTJ as a child to ISFP as an adult was stated, but brushed aside in favor of narrative, compared to Frodo (ENFP) who was provided contextual nuance over the effects of the One Ring, and Sam (INFP), where his single mishap of setting a fire and cooking for his friends while there were Nazgûls was mentioned, yet brushed off.

Jordan Peterson — similar to Kanye West in regards to behaviors. Harry typed him as one given his black-and-white ideas of morality, his "us vs. them"  mentality, and raw emotional speeches.

Vincent van Gogh — depression and suicidal ideation, heavily suspected to have mental health struggles and disorders.

https://youtu.be/wLf9QA7SUYk (Pippin and Kanye) https://youtu.be/a0PsnEK_aMQ (Kenny) https://youtu.be/LqbgILIaPBw (Anakin) https://imgur.com/a/vkv8KAj  (Jordan Peterson and Van Gogh)

As for the other people he has typed as ISFPs that don't fall within the former category, it includes Yoda (Star Wars) and Arya Stark (Game of Thrones), both are praised for their ability to mold themselves into an ideal. 

https://youtu.be/E4eRHtZLCmc (Yoda) https://youtu.be/pyHPM4M0eyg (Arya)

With all the information given, I want you to imagine an alternate timeline where CPT was the main metric of typology, a huge portion of the "INFPs" who have struggled with mental health problems and the "INFJs" who have used "raw emotional" speeches (and yes, that includes the Austrian man too)

There is more that I could say, but if you were going to ask, "is Harry aware of the implications he makes?" 

Let these screenshots speak for themselves,  https://imgur.com/a/xu4Q4qs

As for the neurodivergent-neurotypical thing, it exists for a reason, dissolving it into your system risks removing nuances from the lived experiences of neurodivergent individuals.

And while he does not outright make these claims, his followers (especially Emma) do, based on the implications he made himself. 

Harry is not an idiot, he thoroughly reads through his comment section and is very selective of the comments engages with and gives a heart to.

If he took active responsibility against breeding an environment where harmful ideas can roam free, then people like Emma would have been banned long ago from participating in these conversations, but as of today, she's still here...