Of course, you're right. And I'm reminded this is why we have a GM - to be the arbiter.
That sounds good!
But that doesn't. Really, the occasional bit of mayhem might be fun, but this is the sort of thing there should be a mechanism to discourage (or preferably, stop).
Hmm, but if the players veto the GM's preferred setting (due to not enough mindless violence for their 'taste') then his fun is already ruined. The GM should say what's what - that's fair because he does the work. GMs should not have to run systems, settings or situations they dislike.