You can start with his recent Russian apologia where he blames the U.S. and Ukraine for forcing Russia to invade Ukraine. That might provide some context when you read one of his books.
Chomsky did so much good in his past but when leftism comes up he becomes stupid. He only realized the Khmer Rouge and pol pot were evil far far far after the rest of the world did. Anti-authoritarian leftists getting baited into supporting authoritarian fake leftists: name a better combo.
Chomsky needs to STFU about politics and go back to linguistics - though he’s not popular in linguistics right now either.
Disclaimer: I think the most correct criticism of Chomsky was by Everett, and the following shitshow that ensued is _really_ a shame for linguistics in the Anglo world [0] (Chomsky wasn't the instigator, but his silence doesn't paint him in a great light). Some of the other criticisms are also valid, but often too ideologically tainted or too incorrect to be worth your time (or anyone's time tbh).
I think you have to start with his criticism of Skinner (papers that criticize other papers are often the best and the most informative ones) and his theory of UG, then Everett's claim and Chomsky's rebuttal (sightly weak, but interesting to understand his views on UG). I know UG has been rebuilt (basically his theory was falsifiable, was falsified on the field, then UG people worked on another similar theory that corrected some mistakes), but it was post 2011 and i stopped followed humanities around that time, and never got back into linguistics, so you might want to read about that.
[0] Something similar happened in France with Furet, and the fact that Furet's school of thought still somewhat exist and the debate lasted decades on polite terms without ad hominem is a compliment to historian's values and practice. Saying "critical thinking" and running away from correct criticism is shameful.
The sad part is that these days Foucault is on the same tier as Chomsky in regards to their quality as scholars - and Foucault is a pseudoscientific charlatan grifter.
The new editor-in-chief of CBS News, Bari Weiss, has been publishing genocide denial pieces, pointing ro various children dying in Gaza as false stories. That happened this week, you seem to be concerned that Chomsky signed a petition for Faurisson on the 1970s, that he should not be jailed for publishing his book on the holocaust. Chomsky signed hundreds of letters for jailed Soviet dissidents, Turkish authors on trial etc. That he did not want Faurisson jailed for his book is seen as a bad thing by those who don't believe in free speech and believe authors should be jailed by governments.
Regarding Cambodia, the Khmer Rouge coalition was pushed out in 1979 and the US began arming the KR coalition, providing UN support for it etc. You would think the US and Reagan arming the Khmer Rouge coalition more heinous, if you don't like them, than Chomsky saying the US should not bomb Cambodia in the 1970s etc.
The UN and every human rights organization in the world says the US has been and is involved in a genocide in Gaza. The denial of this in the US has been incredible, but now that the first stage is done the Press is more forthcoming about it. Something Chonsky opposed, the establishment supported.
It sounds like we both agree that genocide denial is a serious matter. By familiarizing themselves with the links I put above, people will be able to make an informed opinion on Chomsky's engagement with it.