Cruz specifically endorsed Roberts, stating that in his opinion, Roberts was a "constitutional conservative." He really believed it or he was lying. I think he really believed it. He was wrong. Ergo, his argument is false.
If so, there is absolutely no guarantee Cruz could know if anyone was a "constitutional conservative." Ergo, there is no guarantee he'd pick judges any better than trump. Even Reagan had a clinker.
And what in Robert's record prior to the Obamacare decision would have indicated otherwise? C'mon, oh wise one, you seem to know things that should have told Cruz what Roberts would do in the future - enlighten us!
Roberts wasn't Cruz's choice for the position, but once the choice was made, he supported it.