(Think carefully. Most people will "want" to answer the seemingly-closely-related question "Why do you think these books are 'ignorance'?", but that is not the same question!)
I would completely agree with what you said about the rights of the private companies if Amazon was a regular market player. But even you qualified above statement. Even though Amazon is not really a monopoly, it is pretty close for small scale book selling. That is, it has such a dominant market share that its decision not to sell a book can be a death sentence for a small book publisher. Thus they should be super careful when culling titles by content -- next time they might pull <insert your favorite hot topic> and there will be no recourse either.
Why do you have to trust Amazon's assessment? You don't have to trust my assessment of anything, either. Nor I yours. So why are you debating whether or not you should trust Amazon's?
I don't agree with plenty of things corporations do. I'm confused on what point you're trying to make?
edit: This is a question if it's not clear. Please answer.
But it is not Amazon's duty to prepare such books in store just in case you want to assess ignorance level of certain works. They are tens of millions of books out there, are we going to blame search engine to not presented all of them to you in order to be, not biased, and supporting freedom of speech/expression/searchability? Probably not.
You’re under no obligation to accept science’s assessment of the facts. But if you choose to reject it, be ready to do a better job of making your case than the scientific community has done making theirs. Extraordinary claims require extraordinary evidence.
I also observe that the censorship frontier is moving quickly and taking a lot of ground in the past couple of years, and while I may not be forced to accept it today, the trend is heading strongly in a direction of yes, outright forcing me to accept a very Amazon-like decision about what should and should not be censored. It's strong enough that I feel it's acceptable for me to not just ignore these facts.
: I mean this globally about Amazon's gestalt opinion, not this specific case. One of my kids is diagnosed autistic and the other has the doctor's scratching their heads and kinda headed in that direction, and my wife and I have both looked at the "autism community", and steered hard away from it. There's all sorts of things wrong in there, at least on the loudest side of it. While I have no specific knowledge of the books in question, my priors have no problem accepting the idea that they are full of stupid and dangerous advice.