You have to consider what would happen if power went out. If everyone for whom power went out dies within a few hours, then yes, I would consider it uninhabitab

You have to consider what would happen if power went out. If everyone for whom power went out dies within a few hours, then yes, I would consider it uninhabitable without extraordinary means of ensuring that the power can't go out (see, for example, the measures taken at south pole bases to ensure power continuity). Power outages are inevitable, and above a certain wet bulb temperature you can't hydrate or shade yourself out of overheating. It's a when you'll die, not if.