"Run them down" seems to be the tweet that got another prominent right-wing personality turfed out of Twitter. Motoring Tip: it's the police that get to kill without consequence, not you. Even if it makes you angry to see black people rioting, and super-angry when they're in the way of a real American's car. Yes, even then!
As is always the case with these things, it's not clear if the ban is permanent, whether it was for that specific tweet or for other reasons Twitter won't disclose, whether Reynolds thought he was being funny, or exactly how sustained the footstamping will be from white supremacists.
(Apart from the predictable, if plainly stupid belief that it's OK to run over "thugs", they're saying that "run them down" means something other than "hit people with your car". For them, the tragedy of speechcropping on Twitter is that Twitter gets to decide what it means.)
UPDATE: Reynolds is back. His account was suspended until he agreed to delete the Tweet, he reports:
Twitter has unblocked my account on condition of deleting the offending tweet. I've done so, but it's here:: https://t.co/DDkZd2el6Y
— Instapundit.com (@instapundit) September 22, 2016