Making a thread non-canon because you didn't like how another writer played? That's just selfish to me. That's something that requires all participants' consent, or at least in my opinion. Who is one person to say what did and didn't happen that other people took time to write? Nopenopenope.
Being ruled death by a judge.... Nah. We're fine, and that is unnecessary and repulsive to just think about. Like Ayden stated in the OP, the PK rule has been taken as an inability to be hurt when in reality, it's an inability to die. If you do something stupid, or even if you make an honest mistake as a writer or character and mess up big-time, you should be able to be put in a wheelchair ICly for the rest of your life and deal with the fact that you were either in a duel or in a warzone, and should have known the consequences.
And the rank tag thing? They're all just that - ranks. I never believed in them, only IC experience and time put into threading/training. Why shouldn't a padawan with ninety threads beat a master with thirty? If they're a good enough writer and their character is realistically clever enough to do it without any personality flaws getting in the way, sure. It's all about what progresses IC. Outranking someone isn't an invitation to be immortal.
Perfect example: NFU's aren't looked at twice as OP when fighting a FU with some degree of equal progression in the thread. But if a padawan, someone more suited in every statistic way than an NFU goes to fight a said master instead of that NFU, it's "Godawan." I bet most people don't even see the subconscious mentality, but rank isn't a substitute for good writing and awareness. I think this works both ways and a lot of high-on's have forgotten that they're mortal too, and a bullet will still go through their body like anyone else's for example. No one is perfect and everyone slips eventually.
Finally, the simple solution to people doing things like storming the gates of a fortress all alone is to ask them to be realistic or change their post - politely - and failing that, report them if need be. It's that simple. I never really believed in avoiding a particular person because of the way they post and the things they post, because then they'll never learn and never get better if everyone is avoiding them, but these things aren't all that complex to deal with. It's just about establishing a good give and take.