Even if you were correct about that, then if we're discussing the possibility of Alicorn's or anyone's outraged/upset reaction to a defense of throwing paint, this only makes sense if this a defense possible to be taken seriously, to elicit a serious reaction.

I do think that Alicorn follows a policy of being offended when people to engage in serious efforts to play devils advocate for positions that she considers to be immoral.

Playing devils advocate for extreme immoral positions is something that some people can see as a game. If you go to the world debating championships than you might get a topic to argue that there should be more genocide. For debating folks making such an argument is a fun game of being intellectually detached from the position that one argues. There are other people who don't think that there use in someone producing the best defense of genocide that's possible to produce.

So, either way, I felt compelled to assume Vulture was saying something I'm supposed to be able to follow without suspending all common sense.

It's possible to win debating tournaments where judges look at whether the participants make rational arguments while advocating positions that are very immoral. It doesn't take suspending common sense to make an argument that not enough people throw paint at other people. It just takes intellectual detachment.