Personally, I'd prefer a system where the judge was given an option to place the ban within, say, a two or three day window, rather than for the ban itself to be automatic. Put the onus on the players to take action, rather than allow the players to sit back idly and let the game do it for them. An autoban by a faceless bureaucrat does not provide any option for interaction or personal choice. Having the judge actually place the ban puts a personal name on that ban. And having a judge refuse to place the ban forces the judge to step up and weather the storm.
And if there happens to be no judge during that time, or the judge is wounded? Too bad for you. Just like it's too bad for you if your judge is wounded and that infil escapes before he can be banned/executed. Deal with it and move on.
If autobans are put back in, I'd think they would be appropriate only for war/hatred relations. If they get expanded any farther, it should be all the way, for every realm change.