He’s not popular with his colleagues. That’s why he’d make the SCOTUS, they’d vote for him to get rid of him. I’d think he’d be a good justice too, he’s more of an ivory tower guy.
If he really is a constitutionally as he and his fans says he is. He would have a far more effective & far longer positive effect on restoring constitutional government as a member of SCOTUS then continuing as senator or even being POTUS. (Which he is temperamentally unsuited to achieve! Note I am not passing judgement on his eligibility! Different issue!)