Maybe I am being dense or not fully getting it, but I am having some difficulty seeing where the conclusion that the guard was being anti-trans is an absolute given and there are no other alternative reasonable explanations. Security personnel are trained to look for anything out of place or unusual as possible signs of shoplifting. In his mind, finding women's clothing in the men's fitting room was unusual so it warranted follow up. If I am reading the post correctly, all he did was to comment about it and ask to see the camera footage, and he did not make any negative or derogatory LGBT comments. He could have been simply just doing his job. I have two friends who have worked store security, and they have some amazing shoplifting stories about the lengths some have gone to steal stuff. Shoplifters come in all forms, and they will try to steal anything if they think they can get away with it or profit from it.
Confirmational bias pushes us to make conclusions that fit our biases. We all frequently do it. I think most will remember when out your first few times en femme, it was hard not to assume every whispered comment you noticed, laugh you heard, or every look you detected was about you getting read and viewed unfavorably. It is a natural and understandable conclusion.
It is a shame the OPs fitting session was spoiled, but IMHO to say the guard's actions or words were symptomatic of the guard's anti-trans bias may not be right.
