What work is the word "racist" doing in that paragraph [...]

The word occurs several times in different contexts; I take it (from what you've said elsewhere here) that you're referring to the instance where it prefixes "ideas". The work it's doing that couldn't be better done by "wrong" is specifying the particular variety of allegedly-wrong ideas I'm saying I think MTGandP isn't trying to promote.

The fact that MT's post is at -7 and AH's comment is at +4 [...]

... indicates that there are some other people who think MTGandP's post wasn't very good (which might be for many reasons), and that there are some other people who agree with AH (which also might be for many reasons).

I repeat: How does any of this amount to "creeping censorship of right-wing ideas"? What specific right-wing ideas? How are they being censored?