Now, I accept it is valid for firefox to warn people when they first come to a site that it has a self–signed certificate. However, it is wrong, indeed clueless, for firefox to imply, by disabling the option to mark the site is valid, that such sites can never be valid.

By preventing me telling firefox to stop being quite so stupid, the firefox warnings are becoming spurious. The encourage me to ignore their warnings, because most of the time those warnings are annoying falsehoods, they’re worse than noise. By getting this wrong, firefox weakens the power of its warnings, so weaken the security its apparently trying to strengthen. This is the mistake.

Firefox should give the warning, but allow the user to tell it, yes, this site is valid.