I generally don't have a problem with it, and sometimes find it fairly funny. Not when people are boring and just use "autist" as a stand in for any given intelligence-based insult, but rather in more specific circumstances. For instance, when a couple of friends argue about the very specific wording in the Dungeons and Dragons rulebook and really get down to the nitty-gritty of it, I myself may well be the one to point out that "now this here is some advanced autism"...
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I'm bored out of my skull, let's play a different game. Let's pay a visit down below and cast the world in flame.