Stupid, or smart?
I mean, put yourself in their position - they pretty much realized there was no way they could escape or get any kind of real concession out of the situation. So, I guess they figured the authorities would give into some trivial demand like Pizza, and that was basically all they could reliably get. So, they ate their pizza like kings, and got escorted back to their cells.
It also does set a precedent that the authorities are willing to give into demands.
Perhaps not as stupid a move as it might seem...