No, not at all, just to leave time to users to deploy the fix before everyone jumps on exploits. This is important because every single backported patch is a candidate for an exploit already, and it's only a matter of time before any of them is exploited. Reason why embargoes have to stay short. It takes some time to figure whether a bug may have security impacts. It takes much less time once this is figured, to develop an exploit.
By the way it could have really happened that the fix for data corruption would have been merged first, and only later the author figured there was a security impact. And the patch wouldn't have been any different. That's why leaving 1-2 weeks for the fix to flow via distros to users, and having the author post a complete article is by far the best solution for everyone.
Thus the only solution is to have a public fix describing the bug and not necessarily all the details, while distros prepare their update, and everyone discloses the trouble at the same time. Those who need early notification MUST ABSOLUTELY BE on linux-distros. There's no other way around. As soon as the patch is published, the risk is non-nul and a race is started between those who look for candidate fixes and those who have to distribute fixes to end users.
This is not about silently patching or hiding bugs, quite the opposite, it's about making them public as quickly as possible so that the fix can be picked, but without the unneeded elements that help vandals damage shared systems before these systems have a chance to be updated. Then it is useful that the reporter communicates about their finding, this often helps improve general security by documenting how certain classes of bugs turn to security issues (Max did an awesome job here, probably the best such bug report in the last few years). And distros need to publish more details as well in their advisories, so details are not "hidden", they're just delayed during tha embargo. Those who are not notified AND who do not follow stable are simply irresponsible. But I don't think there are that many doing that nowadays, possibly just a few hero admins in small companies trying to impress their boss with their collection of carefully selected patches (that render their machine even more vulnerable and tend to make them vocal when such issues happen).
In addition it's important to keep in mind that some bugs are discovered as being exploitable long after being fixed. That's why one MUST ABSOLUTELY NOT rely on the commit message alone to decide whether they are vulnerable or not, since it's quite common not to know upfront. I remember a year or two ago someone from Google's security team reported a bug on haproxy that could cause a crash in the HPACK decoder. That was extremely embarrassing as it could allow anyone to remotely crash haproxy. We had to release the fix indicating that the bug was critical and that the risk of crashing when facing bad data was real, without explaining how to crash it (since like a kernel it's a components many people tend to forget to upgrade). Then after the fix was merged, I was still discussing with the reporter and asked "do you think it could further be abused for RCE?". He said "let me check". A week later he came back saying "good news, I succeeded". No way to get that info in the commit message even if we wanted to, since that was too late. Yet the issue was important.
Speaking of Brad, I personally think that grsec ought to be on linux-distros, but maybe they prefer not to appear as "tainted" by early notifications, or maybe they're having some fun finding other issues themselves. We even proposed Brad to be on the security list, because he has the skills to help a lot and improve the security there. He could have interesting writeups for some of the bugs, and it would probably change his perception of what happens there. Maybe one day he'll accept (still keeping hope :-)).