My tinfoil hat theory is that Trump is Cruz’s stalking horse, out taking the heat early on, raising issues, and will eventually bow out or flame out. He’s sort of akin to what Lindsey Graham is for Jeb. I think Graham is the GOP-e plant for Jeb. He will say the things that take heat from the right that Jeb doesn’t want to say. Like attack trump.
The difference is that according to polls, the other liberal Republicans aren't putting a dent into Jeb's numbers. Graham and Pataki are statistically at zero, Christie isn't much more.
In contrast, the glut of conservative and pseudo-conservative candidates are fragmenting the anti-Jeb vote in such a way that Jeb's nomination is almost assured (other than Trump, every other conservative candidate is hovering around 5%). If anything, the dozen or so conservatives and pseudo-conservatives are unwittingly stalking horses for Jeb.