There was no consensus that the virus was airborne (and mostly otherwise) when Trump supposedly believed it was airborne (well travels in the air). So Trump uniquely ahead of the curve in having an understanding of things, or making stuff up? Uh it's Trump of course it's believing whatever is in his head that day. Trump denotes none of whatever brain power he might have to stuff that doesn't very narrowly interest him. But as for what did he know and when did he know it, that didn't even exist in our knowledge of the disease at the time I suspect.As was in the news.... he has known early on that the virus is by airborne spread.
But suspecting it was dangerous was of course warranted and he suspected it was dangerous and did little about it. That much is true.