Well, first of all, I've stated my opinion, but that's just my opinion. There's still a proposal on the table. I don't have veto power or anything.
Second... Walking away from an adventure isn't always an option. Usually it is; if you're just hanging around Daunton trying to decide what to do next, I think it would make perfect sense to leave if you wanted to. If you're trapped in an active volcano with two minutes until eruption and you can't figure out how to get out... Quitting an adventure at that point is probably not appropriate. However, even if walking away isn't necessarily an option, that doesn't mean you're forced into PvP. You could simply choose not to fight. You might get killed, but you can still stay true to your character. And, this is just me, but if a player stayed true enough to their character to let themselves be murdered by another PC rather than strike a comrade, I for one would be more than willing to bend some rules to do something nice for that character. (Free resurrection by divine intervention? Reincarnated as a deva? Demigod NPC?)
Third... In my ideal world, DMs wouldn't allow PvP to happen without making it clear to players, and getting their approval beforehand, that he or she wanted to run a game where that would be a possibility. For instance, a DM might say in their adventure's recruitment post that they're willing to allow nonlethal PvP if both players consent OOC and it makes thematic sense IC. But this isn't my ideal world, and it's not always going to be that clear. In this world, where player tempers run high and DMs aren't perfect, we'll have to muddle through the best we can.
Maybe the best way for us to deal with that is an outright ban on PvP, but I still feel that a proposal isn't quite the right way to handle this kind of social contract issue. What if it were a poll?