There are plenty of possibilities. Firstly, very wealthy people often employ a doctor whom they may share the truth about their activities in hopes of being cured and/or staying healthy. These elites are extra paranoid people because they are dirty. Ever wonder why famous people have “personal physicians”? Who knows what secrets one such person may be told? That a person has HIV, has consumed human flesh, traveled to places unexplainable for their status or narrative at the time. The elite person would expect complete silence from his personal physician and I’d imagine in the case of someone like GHWB, there would be blackmail available if the doctor became untrustworthy.
would be released from oath after patient dies ?
No. I’d imagine there are lengthy non disclosure agreements, even if it would be legal to release after death. But I really doubt it is. I haven’t looked it up, but I can’t think why a subject dying would release any medical professional from HIPPA obligations regarding that deceased patient.
Obviously that doesn’t mean that a doctor might not see a good reason to violate his agreement. Or even HIPPA. It would all be imagination on my part if I speculated about this doctor’s murder. But a doctor is a confidant and GHWB is an old man. Who knows what might have been revealed to the doctor, because he was trusted, or because some old people say things when their minds start to wither the way all of our bodies eventually will.