Eh... all they can do is temporarily shut it off if the power plant is threatening to overload. When it overloads, someone's losing their power anyway. It's like rolling blackouts, but much more polite.
They gave us a free high-tech programmable thermostat out of the deal, and they have a contract that says they can't turn it off for more than ten minutes at a time, and only ever between the hours of 4:00 and 6:00 in the evening. Most of the time we're not home then anyway. And they send us a report at the end of the year that notifies us of exactly when they had to shut it off, and so far it's only been once each year.