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.
If the sites are taking no action they will be vulnerable no matter when the patch is released. For the people who do take action before chainguard's release the safe option was to just turn off your server (and let any big competitor site stay up and take your traffic since they got the patch ahead of time). People taking this option will be offline until a fix is available for them to use. They are not in danger of being hacked.
Trying to say that uncordinated disclosure is bad because people might get hacked yesterday instead of today just is not a convincing argument to me. I prefer the solution that results in the minimum amount of downtime for sites and sites provide value to society.
I will nitpick on that, if it was just released as a patch, there wouldn't be a hype to begin with, just point update to apply.
I'm just gonna assume patch was ready for a while and the wait time was just letting big players to update their own stuff before it is available for the public, and at that point it is just making the rest of the internet second class citizens not "worthy" enough to get the update quicker.