Malicious people might suspect that United, in a hole, kept digging, and employed folk to hunt for dirt about the passenger and leak it to the Press (even though any oddities in his life - we all have oddities and failures in our lives - are totally irrelevant to the rightness or wrongness of what happened).
Hate to dissuade you of your conspiracy theory, but you need not employ anyone to find dirt, you can do it yourself. In the US many states where medical professionals are licensed have web sites to verify accreditation/good standing. All it takes for anyone interested is a few key strokes.