No, Obama was never a "professor" of con law. He was a guest lecturer, a far cry from a professor. About on par with an associate instructor. He never practiced law to any real degree and he's never even served as a judge. Not even in traffic court. Thus, he's totally unqualified to be SC justice. Heck, he's really not even qualified to be a municipal court judge.
He's not qualified for any profession. Take out politics and he's never had a real job at all.
He's not qualified to run a lemonade stand but that hasn't stopped him so far!