point 3 is some nitpicky claim about Fatal familial insomnia.

I don't find it to be egregious

mischaracterizing the entire disease is not "nitpicky" imo

This doesn't really change anything. The problem is the large number of accusations, not the size of the work being accused of inaccuracies.

I think the point others are making is that you can make this accusation about most topics. Take the average, well-sourced Wikipedia article on a similar topic as an example. Choose it by random. You’ll find the same issue. Every subject has some amount of internal disagreements, controversies, and inaccuracies. There will always be more questions than answers.

You still haven't explained how pointing out 5 factual errors in the first 4% of the book is actually in bad form.

This in particular: "it takes an inordinate amount of time to respond to the criticism"

Ain't it. If you are going to present yourself as an authority on a segment of human knowledge, then you should necessarily EXPECT to receive challenge when you haven't actually done your own homework. Nobody who writes a book while acting as an authority should be incapable of showing their work.

Five is not a large number.

And since they're all aimed at the first chapter, it's not cherrypicking.