This is why embargoes have deadlines. To make the necessary trade-off between "patch as soon as you can, potentially jeopardising the safety of users -- even users of non-proprietary projects" and "wait for everyone to be ready before you patch -- which also jeopardises users". The embargo system deals with this by forcing everyone to agree on a date, and if someone patches after that date then too bad. You may disagree that the deadline was so long, and that could be a fair criticism.
But pretending as though co-ordination of any kind is somehow bad (and then resorting to emotional arguments and so on) is pretty reckless.
I have seen and participated in this disclosure debate for 10 years now. I have come to the conclusion that, in the long run, the least harm approach is full disclosure. There isn't any wiggle room. There are no shades of grey. The whole coordinated response movement is misguided. There are some limited circumstances where it can make sense to delay disclosure, such as creating an imminent threat to human life, but generally full and nearly real time disclosure results in safer software sooner for end users without putting them at some unknown, but high risk level.
3 months is more of a joke than a reasonable time, but one can argue about that if he wants...
> even users of non-proprietary projects
Actually many FOSS projects get only notified on the disclosure date.
Hiding the vulnerability for such a long time makes more harm good. The vulnerability can potentially be exploited by security agencies that necessarily know about them and could also be leaked to a bad actor by an employee of one the vendors.
Hopefully WPA2 isn't that important, but potentially security sensitive users trusted something that was known by some to be vulnerable for 3 months! Bad actors could have used it against them.
The embargo resulted in potentially bad actors knowing about the issue, but not vulnerable users.
The state actor should be least of your worries compared to the millions of script kiddies would could use the vulnerability once it is disclosed publicly.
For most of them the day after, when I get a notification from my RSS app...
No. I also don't expect them to choose device based on security. That is very bad as vendors won't care about patching their older devices (look at Android devices, home routers...) and vendors won't care about patching their flagship devices fast as they have the possibility to request very long embargos.
Making compromises for those vendors and giving more time for security agencies and other bad actors to silently exploit the vulnerabilities (where FOSS projects would have made patches for users that care) is not the way to go. That philosophy actually makes everybody less safe.
But pretending as though co-ordination of any kind is somehow bad (and then resorting to emotional arguments and so on) is pretty reckless.