OK, I live on the street.... but I poop and eat and sleep in a house I bought.
The point is that if you can't get through even a single day somewhere (given some time to prepare and stock up), but you rely on access to some other private property, you don't live (only) there.
Shared toilets are fine. You live in the building (and associated sheds in the case of an outhouse) rather than the single room. Dining might be in another building but you don't have to go there if you don't want to. 'kitchen' is just a name for a room, you can put a rice cooker in any room.
It's not a no true scotsman. The 'can I comfortably spend 48 hours there' test is a pretty good one. Once he adds the bathroom it'll qualify, though it'll be a few more square feet.
And yeah some way to bathe is probably necessary. He'll have that on the dumpster house.
The point is that if you can't get through even a single day somewhere (given some time to prepare and stock up), but you rely on access to some other private property, you don't live (only) there.