I would just keep feeding him (at least a 5 day schedule if you can) and monitor him, without buying him I don't think there's much you can do. I would talk to your manager also and how him your concern, he (or she) may be able to let you do more for it (like bringing in a tub for it, buying better hides, etc).

I looked at the baby BPs at my local Petsmart that they had in the back and one sounded exactly like the one you're talking about: very thin, it wouldn't eat for anyone, stuck shed, etc but they were keeping it in bad conditions - ie, wide open tank, huge hide, heat lamp only, and it was in a room with noisy birds and rodents. I think a good setup would do wonders for it, at least make it feel more secure.