I think it is less about if he actually made any hits on people but rather that the threat existed. The question is not "has such threats been followed through" but "does the person being threatened have a reasonable belief that the threat is legitimate."
To that, I think the answer is an unambiguous "yes". If someone who is rich, well connected, and successfully covering up heinous crimes at a large scale, then yes, I believe a person threatened has a reasonable belief that such a threat is credible.
Seriously, we are talking about a world famous pedo who was pimping out girls to presidents, royals, billionaires, and when he was finally convicted he was only charged with prostitution and got a extremely light sentence that everyone now calls a "sweetheart deal." So years after does a witness have a credible belief that such a man can post a significant threat to her and her family?
Do you seriously believe that no person has any reason to fear Epstein? I find that laughable considering how much conspiracy there is about him being murdered and how the accusations are towards varying high profile people. You're trying to say that Epstein is a puppy dog that's all bark and no bite?
I agree, nothing is proven but it's absolutely laughable to claim that such a threat is not credible.