[mindslight]

I'm overstating it because I'm analyzing it adversarially. But I could very easily see these situations happening emergently. Central HVAC in the main house, then an addition/office/etc that gets a mini split or even its own ducted HVAC. So sure, main AC gets set back 5 degrees but then you're still hot, so just kick the office AC on high and leave the door open.

Also jumpering over a low voltage thermostat takes like 5 minutes tops, and could be easily done by the type of tech enthusiast early adopter that would be interested in programs like these. And it only takes someone getting too hot once to try it, and then just continue doing it routinely. Never mind people for which the few bucks a year is significant.