We actually went through a situation like this personally when my DS was small. He has Asperger's; he is on the Autism spectrum, but is very high-functioning. (He's a college graduate now.) This incident happened when he was 4.
In our case the person whose appearance terrified him was a hairdresser. He didn't love getting haircuts in the first place, but we had to sever a relationship with a shop that we had successfully been going to for 2 years at that point. They hired a new stylist who had a large number of facial piercings and tattoos, and though I'm sure she was a nice young lady, her appearance, especially the piercings, absolutely terrified DS. The first time he saw her, he jumped out of the styling chair he was in, then ran screaming into the back room of the shop and hid under the sink, where he wrapped himself around the drainpipe. It took me 20 minutes to pry him out of there and carry him out of the shop, still screaming. After the second time we encountered her, he flat refused to ever enter the premises again. (I actually had to ask her NOT to try to calm him down; she didn't realize that she was "the monster" he was scared of, and kept trying to ask him what was wrong, which, of course, just made it all that much worse.) It was easy enough to find a new hair salon, but if it was an assigned public school I'm not sure what we would have been able to do.
I'm all for inclusion, but when you alter your body in such as way as to make yourself look somewhat nonhuman, working directly with small children and/or the developmentally disabled is probably going to no longer be a realistic occupational option. They often just don't have the capacity to easily stay calm whilst learning to get past the idea of "scary" things. Stinks, but actions can have consequences that all the goodwill in the world can't prevent.
IDK, that is just me.
