Bumping from the grave..
I just called WotC about this. In my game my player is playing a swordmage and wants to switch to 2h as a free action, attack, then switch back to 1h. WotC said that this is within the rules, although it's up to me if I want to disallow it. I think asked if it's within the intent of the rules or if it's a loophole. He said "it's not the intent and it's not NOT the intent. It's not a loophole either, it's a creative use of the rules". So I will allow it in my game. Also if a monster has an interrupt attack then I will rule that the swordmage is using 2h at that time and will not get the +3 to AC