I think you are correlating impeachment to closely with criminal court. That is a mistake, mainly because it is political inso far as political allies may not vote for conviction if they perceive that it won’t hurt them politically, and vice versa. Also, treason is treason and there is no other qualification. The danger is that the payments can be held against him to affect more policy decisions at any time, and suspicions abound, if not he could just plead that “hey! That was a long time ago.” That simply wouldn’t work. No, now the committees can subpoena the personal bank records and anything else they need to show where and how the money was distributed. Once the public is shown the evidence, if they manage to see it, they’ll be the ones to decide, whether through impeachment or election. It should have happened a long time ago but nobody wanted Camela.