>Chainguard unilaterally broke the embargo and published built images containing the fix.
>This disregarded weeks of work by many parties toward a coordinated disclosure.
Good. Coordinated disclosure meant that people couldn't protect themselves. That's not a good thing. It meant sites were forced to shut down instead of simply updating.
No... Uncoordinated disclosure meant that attackers were suddenly armed with detailed information about an already-hyped severe vuln hours before the majority of downstream consumers had the means to patch their systems.
Maybe your calculus could hold if Chainguard's registry were the primary distribution mechanism for PHP in use worldwide (such that the benefit of an updated image would at least be widespread compared to the sitting ducks relying on the other repositories), but it isn't.