If you post your second scenario as a challenge, I'm quite sure people would come up with several plausible ways for the AI to send a message out. At which point it's game over, given how hackable people's minds are.
I would be very interested to see such a challenge, although I would probably spend longer designing the scenario first.
My point is that there's no reason to assume every possible box can be escaped. Of course, all the boxes we can get cool toys out of the AI can escape from, but still.
Update 2013-09-05.
I have since played two more AI box experiments after this one, winning both.
Update 2013-12-30:
I have lost two more AI box experiments, and won two more. Current Record is 3 Wins, 3 Losses.