Because Cruz was Drumpf's closest competitor in the primaries, and actually beat him in a handful of states, Drumpf's lobs at Cruz tended to be of a highly personal nature -- his wife was a dog (and had mental health issues), his dad helped Lee Harvey Oswald kill JFK, etc. Politics ain't beanbag, but this was also the sort of stuff you don't forgive people for and move on.
And Cruz' endorsement is statistically meaningless; many of not most of his supporters were in the camp as much out of disdain for Drumpf as being for Cruz. The only thing that makes sense here is that Cruz thinks that by strapping on the kneepads, he has a shot at getting appointed to the Supreme Court when Texas bounces his worthless ass in 2018.
And you know what? He's probably right. One thing Drumpf prizes above all else is loyalty -- for a man who apparently has never had a pet, he's clearly a dog person. He just prefers his dogs in human form.
People like Cruz and Chris Christie, who talk a good game but who are utterly bereft of spine and character and actual principles, are more than willing to kneel and do tricks and let master balance a biscuit (at least we hope it's a biscuit) across their noses. They'll eat their own shit and sleep in the yard if that's what it takes. They'd toss the old man's salad in Times Square at noon if it got them the AG and SCOTUS seats they crave so. Their desire to damage this country is as unmitigated and unlimited as their sheer gall.
Scorched earth, people. These fuckers are cockroaches, be prepared to nuke 'em all. No quarter. Beat them like the mangy dogs that they truly are. The "free press" ain't gonna help, so we gotta beat 'em all at their own game, so badly that they can't come back.