You will notice that Obama starts to say Clarance Thomas did not have enough experience, but then Obama realized he did not have any experience to qualify him for the Presidency, so he says he was not a "strong enough jurist or legal thinker". How strong a jurist was Thurgood Marshall when Johnson appointed him. He was Chief Counsel for the NAACP, and he won 14 of the 19 cases he argued before the Supreme Court on behalf of the government, but that make him a jurist? Or a legal thinker (which I would assume would be reserved for people that taught in law school.
As WSJ says
By the time he was nominated, Clarence Thomas had worked in the Missouri Attorney General's office, served as an Assistant Secretary of Education, run the Equal Employment Opportunity Commission and sat for a year on the D.C. Circuit Court of Appeals, the nation's second most prominent court. Since his "elevation" to the High Court in 1991, he has also shown himself to be a principled and scholarly jurist.
Meanwhile, as he bids to be America's Commander in Chief, Mr. Obama isn't yet four years out of the Illinois state Senate, has never held a hearing of note of his U.S. Senate subcommittee, and had an unremarkable record as both a "community organizer" and law school lecturer. Justice Thomas's judicial credentials compare favorably to Mr. Obama's Presidential résumé by any measure. And when it comes to rising from difficult circumstances, Justice Thomas's rural Georgian upbringing makes Mr. Obama's story look like easy street.