Banning someone from a platform is almost never the answer, but in this case I think Jack Dorsey got it right. His biggest mistake was not reacting soon enough. The most common argument against Milo's permanent exclusion from Twitter is that they don't also ban all the racists, jihadists and every person that uses their account to threaten another with violence. My albeit completely unsolicited response to that would be a) that's like saying you can't jail this murderer because you haven't yet jailed all the murderers and b) most people didn't/don't have 340,000 followers to direct at a given target and who were willing to attack that target in the most offensive terms possible.
I've been following Milo Yiannopoulos's 'progress' for several years since he appeared on the horrendous Channel 4 'news' show 10 O'Clock Live as their token conservative guest. He was occasionally an astute, eloquent critic of left-wing pomposity and occupied a rare space as a gay conservative (in the Republican tradition more so than the Tory), but as he realised the outrageousness of his statements was exactly proportionate to the attention it attracted, his views became detached from reality and their sole purpose a vehicle for his own aggrandisement.
The litmus test for whether somebody who makes a living by treading the line between acceptable controversy and outright attention seeking is to imagine them in a world without internet. Would they be successful, or would they be nobody? It's pretty clear to me that the distance between writer and subject afforded by the internet is Milo Yiannopoulos's only means of survival. Without it he'd just be a balloon with the word 'controversial' written on it, slowly deflating in the corner of a fancy dress party nobody came to.
Of course, there's a problem here. The other reason you don't ban people from things is because it only gives them more attention. He will be back, and as and when he reappears we must do our best to completely ignore him.