I'm amazed at all the people insisting it's bad service for the employee to follow store policy when so many of the stories on that site are about customers abusing employees for doing the exact same thing.

If she'd described the customer as anything other than an overweight Trekkie, I wonder if so many people would bother getting offended and up in arms over the sort of post that happens all the time. It's a description, not a damn value judgement!
Makes me think of Comic Book Guy from the Simpsons, actually.

Calling me a pasty-white girl with small boobs would also be neither offensive nor a value judgement -- it's true and a completely valid way to give a mental image of me. Describing someone's appearance =/= discriminating against them.