I haven't read this whole thread yet but I wanted to add that I know a woman with an "emotional support" dog. He is a trained service dog and the woman suffers from post traumatic shock/syndrome. You would not look at her and see a disability but the dog is necessary regardless.
I'm sorry for the OP and the lack of compassion from the FAs regarding his allergies. I also saw some of that other thread and was appalled at the lack at training some so-called service dogs have displayed. I guess a first time flyer can be nervous even if its a dog?
Deb