If the net effect of the override is that users routinely click through the warnings, then the security of the whole system depends on how well we can educate random end-users on the TLS security model. That's not going to work.
I feel like we're talking past each other. I'm pointing out that when a user is under attack, they're not getting what they clearly stated they wanted. The only conundrum here is that the browser can't tell the difference between "under attack" and "misconfigured". If you want to bang on that conundrum, OK. But this business about user intent doesn't make sense to me.
But the the user is more often than not, not under attack. Think back to the last ten or so security warnings you go while browsing the internet.
How many of them were a result of a pretty blatant configuration error? Things like self signed certs on personal/toy sites, T+1d expiration, subdomains using the main domain's cert (or vice versa), bad local clock, things like that that?
How many of them were ambiguous?
How many of them were unmistakably fishy?
If your breakdown is anything like mine, it'll be 9/1/0.
I speak of intent because the original person I replied to suggested that security warnings should not be dismissable. I vehemently disagree, because it is my decision to make whether accessing the information I clicked on is more or less important than the risks for the particular class of cert problem that presented itself.
Hide it behind an about:config variable or explicit cert trusting or something else, I don't care. That is still superior to telling me that I can't access something for my own protection.
I'm more sympathetic to this argument, and hiding it behind an about: variable seems like about the right way to handle it.
In fact: apart from the sheer ugliness and cryptographic ass-backwardness of the protocol itself, this is my biggest problem with DNSSEC: it takes the exact same set of failure modes and migrates them to the DNS, where there is no error recovery possible. When DNSSEC configurations break, sites simply vanish from the Internet.
