I really, really doubt you and Con have anything to do with it. I bet she plucked because they moved her into that back room and she's upset.
I know how much you want to save this bird. I feel really bad about how things are going. And you do need to quit. Having a bunch of ignorant people questioning you all the time has to really get to you. It would me. That and I wouldn't want to see how badly they treat the animals.
It also sounds like the vet there is not familiar at all with birds. My vet says they don't teach birds at all in vet school. Now some non avian certified vets go ahead and learn a lot of the material on their own and do pretty well with birds. But, most don't. They just try to do the best they can based on what they know about other animals, and that may not be good enough. I know I feel a lot more confident in my new vet who is avian certified than I did with my previous one, who wasn't, but was a breeder. He did fine, nothing bad ever happened to any of my birds and he managed to treat them. But, the new one tells me a lot, shows me the slides on the microscope and actually went over every single thing on the blood panel with me.