From a public policy point of view because they take advantage of legal protection offered to internet businesses that act as a form of public utility to shield themselves from the liability that they would otherwise have for publishing the material they do.
exactly... even if there were a conservative twitter, the company would have to censure. What the alt right pranksters want is the ability to troll for fun. That’s what 4chan and 8chan are for.
As another poster FR bans posters regularly. I think you’d agree it shares whatever “public utility” benefits that Twitter has.