That was a leaked Blu-ray Processing Key that was quickly revoked - but the industry was livid that it was allowed to propagate before they could revoke it (which takes 90 days). This means, ultimately, that if you have a player that hasn't had a Blu-ray Disc made since 2008 inserted into it, and are trying to decrypt a disc made before ~2008, then maybe with the right tools you could. It's a shallow victory meaningless nowadays.

[Even then, a Processing Key isn't nearly as interesting as a Device Key, plenty of which have been leaked since without much attention. Blu-ray has so many keys...]

Stripping Blu-Ray encryption works just fine with MakeMKV (and other tools). Even UHD disks if you have a LibreDrive-compatible reader. Sure, it requires someone to decrypt the individual disks keys and distribute those but in practice it just works for anything that is not a brand new release.