I think that both motives are possible.
As a side note, the fact that the doctor was selected as the attending physician to a president means he passed a number of background checks for both security concerns and being potential for scandal.
Thus, quirky, potentially high risk lifestyles on the doctor's part such as high levels of personal debt, friendship with criminals, substance use, lawsuit prone, dubious investments, high stakes gambling habit, involvement in love triangles etc. can probably be eliminated.
That leaves, as other posters have mentioned, the two possibilities you listed and the possibility of a dispute stemming from his medical practice.