I think the POTUS has a compelling need to save valuable time while in office by streamlining what he can and can’t move around to get the job done, but that compelling need ceases as soon as he’s out of office. We’ll see how this goes, but I’m thinking the needs of the nation to keep its secrets outweigh the desire of the ex-president to hang onto stuff he isn’t involved in anymore.
He is totally allowed to have these documents just the same as every other President. If you cannot see that this is nothing but a corrupt witch hunt then you are playing for the other side.