Yes, yes, I get the "Me first!" thing -- like many consumers, you want your demands fulfilled and if they aren't met to the letter, you threaten to take your business elsewhere. Honestly, many retailers hope for that, as they prefer not to deal with customers who have crazy self-entitlement issues. I know that's blunt, but there you have it. Good customers don't attempt to take retailers hostage (i.e., they don't make demands and threaten to take their business elsewhere if those demands aren't met).
That said, yes, there are bad retailers -- I'm simply not sure that a failure to stay open past posted hours in order to assist newcomers is a qualifier for that. Again, posted hours are posted for a reason. The responsible consumer calls ahead to see when a store is open. They don't show up unannounced and then expect the establishment to extend their operating hours just for them, threatening to never again visit said establishment when they don't. That's bad consumerism.
Again, these are the customers that most retailers (not just your FLGS) would glady pay to get rid of.