there is a lot of crappy RPG players out there, believe me I have met my share of them over the years (being gaming in one system or the other since 1981)
For living campaigns, you HAVE to stick to your guns and follow the guidelines of the adventure. But these will always be those that feel they are above the rules and there is only so much you can do about those players.
IF you want to be a "total dick" about the situation, you could make a point to find out which other hobby stores in the area offer living city campaigns and stop by to drop off a list of names and descriptions of the players so that future GMs can keep an eye out for them....

People that have a rep for being asshole players generally find themselves banned from hobby stores as it is harder to find GMs then it is to find players.... and most hobby store owners realize that a good GM will BRING players to their stores.. which means an increased chance to make sales...