The title states "1989".
IMHo, Jackson could never be elected President or Vice President.
However, it's remotely possible that Jackson might be named to a Cabinet position by a Democrat President. (Not Dukakis, he wasn't that stupid.) Then if a terrorist strike or natural disaster killed everyone ahead of him in the line of succession, he could become President. Part of the difficulty is that while Jackson would be unfit for any Cabinet post, he would be extremely unsuited to any of the senior posts, such as State, Treasury, Defense, or Attorney General, and nor suited to Agriculture, Interior, Commerce, or Labor. HHS, Education, or HUD, maybe, but now the strike has to kill (or incapacitate) at least ten individuals.