Well, we might not want to say "any patch on trunk can be backported to any branch, no problem" because that can often have undesirable side effects.
But I think we should certainly say that any patch approved to land on a particular branch (but not yet landed there) can be applied by anyone packaging that branch. That alone wouldn't have helped here since there was an extra problem --- the branch approval request was ignored for four weeks :-(. That was simply a mistake, people should never sit on requests for long. But if you read the Mozilla bug --- https://bugzilla.mozilla.org/show_bug.cgi?id=550455 --- there's not much communication from Fedora there. Just one comment on the 23rd saying this matters to Fedora, and the patch was branch-approved five days later (which is definitely too long, but not outrageous IMHO). A more detailed hurry-up nag, especially if it happened earlier, would have really helped.
So what should have happened IMHO is as soon as the Fedora packagers realized they needed this patch, they should have commented in the bug "our users are hurting and we need branch approval for this patch NOW NOW NOW", that approval should have been granted immediately, and then via a previously clearly-communicated blanket approval to use such patches with our trademarks, Fedora would have packaged the fix.