As the house supervisor, you really can't overrule a physician, but you can
go up the administrative food chain, to the nursing director and even the administrator if need be, if YOU think the pt. needs additional medical evaluation. The question to ask here is, does the hospital in question receive federal funding? There are law that prohibit patient "dumping" at any hospital which receives Medicare or Medicaid funding; it includes the obligation to treat and stabilize patients without regard to their ability to pay. Such a hospital cannot make policies that turf patients to other facilities in this manner, so the 30% rule can't be enforced (by the ER doc or anyone else).
That said, in the real world, uninsured patients often DO get the 'treat-and-street' type of care, and in all likelihood this patient would be sent home after a perfunctory exam by the ER physician no matter how much the man's daughter protested.
If you took it a step or two further, the patient COULD have something seriously wrong that goes undiagnosed and leads to permanent disability or death, which would undoubtedly result in a huge lawsuit and bad publicity for the hospital........but if you've advocated for the patient and family and been overruled, you can't really be held responsible.
I don't know if that answers your question. Good luck with your studies.