Assuming it would be operating under 14 CFR Part 91 like the rest of general aviation, I think the law is quite clear:

91.119: "Except when necessary for takeoff or landing, no person may operate an aircraft below the following altitudes: (a)Anywhere. An altitude allowing, if a power unit fails, an emergency landing without undue hazard to persons or property on the surface."

91.151: "(a) No person may begin a flight in an airplane under VFR conditions unless (considering wind and forecast weather conditions) there is enough fuel to fly to the first point of intended landing and, assuming normal cruising speed - (1) During the day, to fly after that for at least 30 minutes; or (2) At night, to fly after that for at least 45 minutes. (b) No person may begin a flight in a rotorcraft under VFR conditions unless (considering wind and forecast weather conditions) there is enough fuel to fly to the first point of intended landing and, assuming normal cruising speed, to fly after that for at least 20 minutes."

And it's not like it hasn't happened before. Small aircraft land on houses with enough regularity that I would expect the law to be well settled. See [1] and [2] for recent examples.

[1]: https://www.nbcnews.com/news/us-news/family-4-people-killed-... [2]: https://abcnews.go.com/US/911-call-captures-race-free-woman-...

Drones are pretty good at landing themselves these days if there's a need. I can't imagine one of these couldn't enforce a height limit when it's low on fuel and then land itself when it's nearly empty.

Absolutely right