But the more salient point is that Paul calculated that, given his dad’s record, he had to do everything he could to prove he’s a loyal Republican. His branch of the libertarian movement was uneasy with, and hostile to, the GOP establishment years — decades! — before it ever occurred to Ted Cruz to talk about the “Washington cartel.” Ron Paul ran as a third-party candidate in 1988! Rand worked on his dad’s campaign.
And in fairness, Rand Paul has worked very hard to prove he is a loyal Republican. Sure, he supported lots of tea-party guys in the primaries, but the moment there was a winner, he endorsed and campaigned for him or her enthusiastically. I always took his “big tent” talk to be a marker: If and when he won the nomination, he could point out his team spirit and demand the same from his opponents. It was a good strategy, and at least in part a sincere one I’m sure.
But then here comes Trump (and Cruz, but that’s a slightly different story). Trump craps all over the Republicans. He openly refuses to swear fealty to the party. And Republicans eat it up!