No that’s the problem. Once someone is in a hospital there’s a paper trail a mile long. If you wanted to assassinate someone then the hospital is the last place you would do it. You’d need to pay off a hundred people and hope none of them ever decides to talk. Or you start killing them off but then how long does it take big data FBI to connect those dots?
If guy number 2 was somehow DOA at the hospital or already infected with something irreversible then you’d have a case. But flu to hospital MRSA case to Stroke just isn’t how anyone who cared about remaining free and anonymous would kill someone.