No one without judicial experience would be nominated, and certainly not confirmed. Especially with the politicization of today. Not having the right judicial experience would be an easy grounds to knock out a nominee.
Besides which, such a nominee, even if confirmed, would not be able to have the right kind of influence on the court.
Maybe if he had chose a different path in life, Cruz could be on the Supreme Court. But, as it stands now, he would not be a good Supreme Court Justice. He might make a good, president, senator, governor, or congressman, but not that.
Cruz’s career is of a Constitutional Lawyer. If you didn’t intend to go to the SCOTUS if the option became available, why did you choose that career path. I can understand being in the Judiciary or Legislature (Senate or HoR) with a Constitutional Law background, but not the Executive Branch.