I'd say this worry stems from "Killary".

Democrats know that the prosecutor washing up on shore the day before trial with a bullet in the back isn't a suicide. I think they are or were more afraid of Clinton than Epstein (if they're not actually not just the face of the same syndicate).

So they think "well Trump is unhinged and hates me, I could be next". Maybe he would if he could, I don't know, but Trump can't even hide an affair and get away with it much less a murder.