So…if the memo that he is presenting as evidence that Trump worked with the FBI is the memo that he is also saying nobody, not even the mob, would be able to tell that he ever worked for the FBI then how in the hell is it evidence that he worked for the FBI?
He is speculating and telling you to assume what he is saying is true and that even though nobody else can tell, he can and then presenting it as fact.
Learn to tell when you are being misled or you are always going to end up being misled.