That's the first thing I thought about.
His budget of $432/mo doesn't include health insurance. But $5K/y probably gets him Medicaid eligibility. Let's assume he's on Medicaid, then. In NY state, that covers quite a lot of dental care, if you believe this: https://www.health.ny.gov/health_care/medicaid/program/denta... Not saying it's a good option, but it's there.
> Taking the bus that goes 3 times a day is one thing, needing to move stuff is another thing.
What kind of things do you think he might be moving? He probably has just about no possessions with that budget (and a 600 sq ft house). In a pinch, perhaps he can rent a truck from Home Depot. Apparently, there is a Home Depot in Massena, NY, so maybe it's not quite so far out in the boonies as it seems.
Personally, I wouldn't do it - the lack of choice would get very unpleasant very fast. But it could work for some.