Note that the AI box setting is not one which security-minded people would consider "competent"; once you're convinced that AI is dangerous and persuasive, the minimum safeguard would be to require multiple people to be present when interacting with the box, and to only allow release with the assent of a significant number of people.
It is, after all, much harder to convince a group of mutually-suspicious humans than to convince one lone person.
(This is not a knock on EY's experiment, which does indeed test a level of security that really was proposed by several real-world people; it is a knock on their security systems.)
I think this is making a five-inch fence half an inch higher. It's just not relevant on the scale of an agent to which a human is a causal system made of brain areas and a group of humans is just another causal system made of several interacting copies of those brain areas.
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.