Well, if Bill has no protection agency, depending on the rules of the community, Dawn Defense would likely not be able to simply "convict" him. The free market in any developed town would almost certainly foresee this possibility and, as there is money to be made, have a service of temporary, one-off representatives, I imagine. These representaives could be paid back later, or be paid from a community pool. There's an incentive for private property owners in the area to contribute to said pool: if Bill damages them or their property in some way, they can be recompensed.

Even if Bill truly could not afford a security firm (hard to imagine in the absence of the state as so much money would be flowing thanks to the lack of bureaucracy/taxation/licensing fees, etc.) it is my view that the free market would provide some alternative.

It is ultimately, as you said, Bill's responsibility. It is my firm conviction, though that there would be many incentives, both economic and social, to help bill get covered.

If Bill cannot be covered, he might be forced out of the area, as, in theory, the whole community would be built on private property. If Bill has family and friends, or is a decent guy just down on his luck, this is highly unlikely to happen.