In this case I'd say a troll is a person paid to disseminate misinformation in the interest of a certain ideology. I vacillated on RC; he's quite amiable as trolls go (as opposed to, say, Marty of yore.) But every so often he'd suddenly interject a baldly propagandistic comment, and the specifics of this particular act of plagiarism convinced me that he's a bad actor who should be ignored.

Whether the Mueller investigation will lead to impeachment is a separate issue from whether the investigation will reveal activity that rises to the level of collusion. Indeed it has already done so.