> I'm guessing not likely, given that they've really done nothing about ISIS accounts in the past

This is inaccurate. The precedent for removing extremist content was set in the late 2000s when Facebook, Google, and Twitter started massive campaigns to investigate, report and remove Islamic extremist content on their platforms. A lot of legitimate non-extremist Islamic content and users got caught up in the censorship. I didn't hear anything about it from free speech absolutists, though.