I only just saw this thread
Yes what a silly cow. Glad she was sacked. I don't think it would be easy to take it further. It would require the name and address of the employee and that is confidential information. I think if the store had done nothing about it then there must be some way of forcing them to disclose...but not sure how.
Not all changing rooms have curtains though. I am not bothered either way. As a customer i wouldn't complain if i thought there was a trans person in there. TBH people rarely are looking at anyone else, it's a functional thing, just get the job done, does it fucking fit? Sweet i am out of there. If anyone was looking at me in a changing room, regardless of what sex they were i would likely ask "what the fuck are you looking at?" if i was in a bit of a bad mood. If i was feeling playful i would probably say something a bit tongue in cheek like "what do you reckon then? the black one? or the blue?"
What would be fun would be to set the silly cow up? I mean get a real biological female, perhaps a bit masculine in looks, to go in there and then when the assistant approached