Probably, though determining his qualification as a judge is not something I'm qualified to do. The reason its insane to list him as a potential nominee is because Ted Cruz has said some very nutty things on Twitter. The guy has outed himself as a crazy and petty person and has absolutely no chance of getting any position other than the one he is incumbent to. Ever. Most especially not to the supreme court which is arguably still comprised of individuals independent of politics and believed to be of sound mind.
I don't think Cruz is nutty and and petty, but he is a politician, and his relationship with the American people is that of a politician, and not as a justice.
Putting Cruz on the Supreme Court is like putting Trump in the White House. They may get the job done excellently, but it will change the perception people hold toward the establishment.