The page only mentions that you're obligated to report it to them, not that you're not allowed to further publicize it (unless I missed something).
The subsequent sentence on the page also says that if you find a vulnerability in a third-party app you have to tell the third party.
> For a reported security vulnerability affecting any Apple platform to be eligible for an Apple Security Bounty award, you must not disclose it to anyone other than Apple until after Apple has released a software update and published a security advisory for the reported security vulnerability.
Which does not have the meaning of prohibiting disclosure to third parties or the public; it only means that you forfeit the bounty.
"Apple reserves the right to immediately end your participation in the Apple Security Bounty program if you violate any of these terms and conditions as determined by Apple"
Entirely reasonable.
They can report it but have to wait until it’s fixed.
I think anyone angry about this is just looking for reasons to be angry. I also doubt the people complaining the loudest are even the targets of this program.