I would say that an academic is anyone who has an academic appointment (no self-appointed academics). So I guess I would say that he was briefly an academic. I don’t know (or care) much about his academic career, but I will assume that he was not a distinguished academic (which is what I think you describe). And I don’t care.
There is no evidence that distinguished academics make good presidents, and not much evidence that academics of any sort make good presidents. I can think of just two – Garfield and Wilson. Some people like Wilson, but I never cared for his sanctimoniousness.
The great presidents – in my opinion – were Lincoln and FDR, with Teddy R close behind. Teddy and Lincoln were very smart; FDR was clever, and he knew how to recognize and listen to people who were smarter than he was. None was an academic.
I bet your favorite president wasn’t an academic, either.