Any judge in NY would call hot water required for human habitation by invoking “common sense” based on human body’s propensity for hypothermia under colder temps

I'm not sure that particular argument works that well. You won't go into hypothermia because you don't have hot running water. It would be better argument for fixing the heat.

It's certainly something that's reasonable to assume to be working though, so I think “fit for uses reasonably intended” is the sounder argument here.