I'm convinced that there are enough reasonable, civil people in the world that I don't have to pucker up to kiss the behinds of those who can't behave with a modicum of decorum when their expectations are slightly undermined.
The problem isn't the people you "fire" directly. It's that those other reasonable, civil people might wonder where exactly where you draw the line, and justifiably avoid you based on not knowing. There's enough folks in this category that you really have to be more careful unless your product is truly out-of-the-park stellar and one-of-a-kind.