He just says whatever is in his mind at the moment without trying to connect it to something he's said before or had been told in the past.
You’re assuming a knowledge base that is equivalent of that of the average freeper.
I see two main situations here, either (1) bumbles (he really doesn’t know — his proposal to punish killings of the police with a uniform death penalty is of this kind) or (2) new proposal (he’s still trying to home in on a solution that hasn’t been finalized yet — his healthcare ideas are one prominent example).
Trump memory is not sheerly stateless. How could he possibly run a business that way? He’s already said he views politics as wide open. This is like making a proposal to create a business that doesn’t even exist yet.