It might be useful to inform an admin to look at suspicious postings, especially if they can get the accuracy higher. BUT I hope no one uses such algorithms to automatically stop suspected trolls. This can only lead to unforeseen consequences and stifling of free speech (unless of course stifling is not an unforeseen consequence, but an intended one).
Moderation at a privately owned/operated site can be freely used to filter anything they don't want their users to see, even if it creates a slant. However, the odds that they will start filtering specifically subversive content is pretty low, since it's those kind of posts that generate hundreds of follow-ups of disagreement, bolstering even more traffic. More likely, they will filter the truly atrocious (bland death threats, etc) that add little in terms of desirable content.