I agree that asking US intelligence agencies probably wouldn't produce anything worth reporting. I also agree that there is an asymmetry here, and that it would be very difficult to prove that he was not working for an intelligence agency.

The reporting I'd like to see would probably focus on finance and connections. How did Epstein make his money? Who were his clients? What did his business associates know about the sexual allegations? Who does Acosta claim told him? What were Epstein's internal motives?

I haven't seen any major news outlets focussing on these aspects. The simple explanation is that they fear that any explanation of Epstein other than "he's a monster" would reflect badly on them to the public. The more conspiratorial explanation is that the answers would reflect badly on people who have power over them.

But answering your questions: Yes, I probably would have seen that reporting if it existed; No, it wouldn't be convincing; I don't think the number of agencies matters, the connections he does have seem to lead to the CIA or Mossad.