Being sentenced to thousands of hours with a Federation counselor wouldn't be so bad, as long as her name wasn't Troi.
I don't know if he was tried for treason, but he clearly should have been. He used his position as a Starfleet officer to aid a terrorist group. Other Maquis, like Chakotay, resigned their commissions before joining the group. If Eddington had done the same, I would have liked the character much more.