No one has caught this apparently, but watch the CBC bit of the presser again. Not only did 45 not know what CBC refers to, when he heard the name, Congressional Black Caucus, he only heard "black." He did not know or guess that it's a group of Congresspeople. He took the question to refer to some stray advocacy group that particular reporter had some particular interest in. I don't think this was an "all black people know each other" thing. I think that, since he never heard of CBC, he figured this reporter's "special" interest in them meant she knows them and there was no reason he SHOULD know them.
I'm not saying 45 isn't racist. He's the worst kind of racist, the kind who is oblivious to his own racism. But THIS gaffe was far more about his being completely uninformed and too incurious even to wonder if the "Congressional" in the name meant they were in Congress.
I think people didn't even think of this explanation, though it scans, because none of us know anyone who is that stupid, so completely unprepared for their job.