Why do these kinds of headlines keep getting posted suggesting that Trump is being forgetful? He's not, he knows exactly who was in charge, but he knows his base is stupid and will get riled up at anything he wants to tell them.
It's just a constant stream of outrage to keep the base riled.
I am not suggesting for a second that he's completely sane or that dementia isn't taking hold, I'm merely pointing out that this kind of thing has been his MO for decades at this point. Truth never matters to him or his base.