I think things may have changed enough to overcome that. Mitch getting accosted by Liberal Fascists while walking to his car from dinner is one of the key events. A year and a half an nothing substantive from Mueller regarding Trump is another.
The GOP has very little margin for error in the senate. Flake, Corker, J and C McCain, and gop deep state sympathizers on the intelligence committee. Trump should also consider whether making a move against RR at this time would give dems ammunition for midterms.