Here's the thing about trying to use that audio of Hersh to rehabilitate Malia Zimmerman's story on Seth Rich (which Fox News retracted but never addressed). Even if you put aside Hersh's subsequent denials (and the fact he's a bit of a bullshitter), the story just seems really unlikely.
The story is that the FBI examined Rich's computer shortly after he was killed, found definitive evidence that he was the source of the leaks, and wrote an official report to that effect. The Zimmerman story differs in some details from what Hersh said but they agree on those details. Rich was killed two years ago, and the Zimmerman story was in May of last year.
So to believe this, you have to believe that the FBI had smoking-gun evidence that Rich was the leaker at the start of this whole mess, produced a document saying so, and then suppressed that finding to deliberately frame Russia. Also that document, a year and a half after it was written, 9 months after the Zimmerman story, and half a year after the Hersh audio leaked, has not leaked or been corroborated by any credible subsequent reporting, despite there being at least one person with access to it who was talking to Hersh.
If that document exists, the Zimmerman story and Hersh audio should have turned it into the holy grail for right wing media, but there seems to be no urgency in following up on it. At this point it has all the signs of being the new Whitey Tape.