FF, but very misguided. He's in for a rude awakening next month.
Consider this, Brown Line. I'll give you two scenarios:
a. Trump is nominated, loses presidential election to Hillary, Republicans make gains in 2018 and have a major chance at winning back the presidency in 2020.
b. Romney or whatever token establishment candidate is airlifted in at the convention, causing the already volatile Trump supporters to get even worse, with possibilities of riots. Due to this, Trump supporters don't turn out for Romney, handing the election to Clinton by a landslide, and their voices only get louder in 2020, virtually guaranteeing that a Trump-like candidate, if not Trump himself, is nominated and gives the Democrats four terms in a row.
Are you seriously daft enough to think that scenario B is better than scenario A?