Been wondering too.
He was a bit #neverTrump before he left, so maybe he didn’t feel welcome anymore.
Perhaps it was his way or the highway regards DT.
I noted his active participation, along with other familiar handles, on a competitive site that is “never Trump”. That was about a month ago and when I discovered their views I departed after a short post. Couldn’t believe it then or now as I thought these were patriotic folk.