They had some kind of environmental problem with their storage tanks, and after a few months of "gas sales resuming soon", apparently they found that it would be too expensive to fix the problem, and its been that way ever since.
It is really puzzling, because not too far away on the other side of the street there is a gas station/convenience store/Subway that DOES sell gas, and has a much more varied stock. I have no idea why anyone would choose the no-gas store instead.
The street is one of the main entry/exit streets for the town. People coming into town will pass the no-gas store first, but will be able to see other store just a little farther down, and it is on the same side of the street they are on, so it seems the more obvious choice.