Re: I have some questions
It's dangerous trying to predict what the courts would do.
A simple reading of the federal law against blackmail - USC 18 section 873, which is quite terse - suggests that it's only blackmail if the threat is to inform [whom? anyone?] about "a violation of any law of the United States". Here the threat was to inform the public of potentially-embarrassing information; AMI aren't claiming (as far as I can see) that the new revelations would show Bezos breaking any law.
On the other hand, in the US, it's widely accepted that everyone is breaking the law all the time, thanks to many poorly-defined laws. So a prosecutor might be able to stretch this into blackmail that way, though I'd hope a judge would be reluctant to allow that.
Bezos has explicitly called it a blackmail attempt. AMI has explicitly called it "good faith negotiations", their understanding of "good faith" being extremely liberal.
Perhaps more interesting is speculation that this is a violation of the agreement AMI reached with federal prosecutors some months back, giving them immunity from prosecution for possible misconduct during the Trump campaign in exchange for their cooperation. So it's possible the US Attorney for the Southern District of New York will open an investigation on those grounds.
Of course this won't change anyone's opinion of AMI - Trumpists like them, most other people who pay attention don't, and the tabloid-reading masses just want their fix. Bezos probably gains some net approval, just because people like seeing someone show a little backbone and stick it to a bully. AMI and the Enquirer might get fined or a similar slap, and it's conceivable that one or more lawyers might get sanctioned.
Biting the hand that feeds IT
