What idea do you think I'm doing that to?

In the ancestor you wrote:

Having said all that, I'll add that in fact I don't think it likely that MTGandP is a racist or that s/he wrote that post in order to bolster racist ideas, and I think that if anyone downvoted that post because they wanted to discourage a nasty racist (rather than, e.g., to discourage other people who are nasty racists from posting similar stuff) then they made a mistake. But the point is that the downvotes don't look to me like censorship of right-wing ideas; they look to me like some combination of (1) finding the post unenlightening and (2) seeing it as promoting racism.

What work is the word "racist" doing in that paragraph that couldn't be better done by the word "wrong"?

But let's suppose for the sake of argument that (1) Andrew Hickey was in fact intending to dismiss MTGandP as quickly as possible and to get him (note: actually I have no idea whether MTGandP is male or female; indeed the name rather suggests a collective) to drop the subject, and that (2) such behaviour is very atypical on Less Wrong. What then? How does this indicate "creeping censorship of right-wing ideas"?

The fact that MT's post is at -7 and AH's comment is at +4 rather than the other way around suggests the problem isn't limited to AH.