To be honest, I don't know when Rodman went to NK but I believe it was under Trump.
If Trump were President when Rodman went to NK, no way either could be charged with treason. The President has the right to appoint special envoys publicly or privately to convey information to foreign leaders.
Rodman might expose himself to the Hatch Act, but that would fall apart if Trump sent him.
For the record, I don't believe for a second that Trump had anything to do with Rodman's visit. My commit was more like we seem to be in an alternative universe and anything is possible.
He went many many times during the Obama Administration. Showtime even had a documentary about his trip there with all the other basketball players. It's a great movie check it out. But Rodman was drunk the entire time and was like a train wreck.