Twitter seems to really drag their feet deleting accounts of Islamic radicals inciting violence and Black Libes Matter sympathizers celebrating cop killings. If they even bother to do anything.
If you're going to police speech that's merely provocative, as Milo's is, and not expressly illegal (direct actual threats, child porn, etc) then you're going to get yourself in a position where you eventually piss everyone off. Twitter and Facebook are doing an excellent job of that at the moment with conservatives. We'll see long term how many users want to hang around a dry leftist echo chamber.