We all know Jebby has been chosen to lose. It is fun to watch Trump stir the nest and expose the rats.
Trump helps Jeb.
He takes votes away from responsible conservatives running for president.
The RINO/GOPE vote will eventually coalesce behind Jeb, although I think both Christie and Kasich draw from the same well as Jeb. So...Christie and Kasich take votes away from Jeb. Trump takes votes away from the conservative candidates because he sounds like a conservative even though his track record indicates otherwise.