Part-time lecturer sounds pretty close to the lowest rung to me. And I’ll repeat - if he had a great academic record, he’d have released it long ago.
Nagorsky said there is a major distinction between a lecturer and senior lecturer, though neither is a full-time position. She said the status of a senior lecturer is "similar" to the status of a professor and that Obama did teach core courses usually handled only by professors. Obama's appointment was not part of an academic search process, and he did not have any scholarly research obligation.
Translated to me, the underlined part that highlights the difference sounds like he was not hired on as a professor because of his knowledge or any other 'scholarly' designation or knowledge that would happen with a professor, he was just granted a job. It seems to me they are saying here he wouldn't qualify as a professor.