Anecdotally, we are paid $10/mo for the utility to have the option to disable our A/C for up to a couple hours a day. They do not pay us for the time they actually disable A/C, but I don’t it hasn’t actually happened yet, so we are “winning” that bet. I think that customers would bid this option lower than $10, given the option, but agree others wouldn’t touch it. I hope that the price mitigated the real risk of supply planning skew mentioned by the GP.

I would only do it if either I actually controlled the software that did the turning off or there were a third-party that could be trusted to monitor and provided an escrow account with a huge financial penalty payable to me if the utility ever broke the rules.

I have absolutely no reason to trust them unless their incentives align with mine, and, here, they do not.

Even in that case, I would only agree to the 75F limit, because, for the other ones, it would take way too much time (and possibly too much energy, as well) to get back down. Air conditioning isn't instantaneous, and one can't just turn it on when one needs it, if there's more than a trivial temperature (or humidity[1]) drop.

[1] For some areas of the country, that's another, bigger problem with allowing an outsider to turn off the AC: go too long without and the humidity goes up too high. Now you have to buy a thermostat with a humidistat, just in case, even if you didn't need one before.