They know he's going to fight it and draw a lot of attention, so what's the worst that happens for Twitter? A few rabidly committed Milo fans boycott it? I left earlier this year but I never used it, so I didn't impact Twitter at all.

On another note, it would be kind of sad to see Milo sell out and return to the polluted mainstream. I'd prefer he took his clout to a truly free-speech platform like Voat, or focus on writing and making videos.