Treason
You and a lot of others had better be damn careful invoking the actual definition of "treason," here. In case you hadn't noticed, the bar for "aid and comfort to the enemy" has gotten a hell of lot higher in recent years.
We weren't at war with either Iran or Iraq at this time, and if simply negotiating with terrorist states makes one treasonous, we might want to take a new look at the Baker-Hamilton report. Or the Speaker of the House.
You want to make a case for Reagan simply doing something illegal, you'd have something. The Democratic Congress passed the Boland Amendments, which mandated allowing the Soviets and communists to take over Nicaragua without opposition. Reagan did violate that.