Although many contact allergies are not life threatening, per se, they can cause skin breakdown which can become infected, and if it continues over a long period of time it can become life threatening. Aside from being extremely uncomfortable and even painful. Many people can develop contact reactions after multiple exposures - knew a nurse who was allergic to penicillin, and after years she became so sensitive that she couldn't even touch someone who was receiving it without wearing gloves - it was in their sweat. She finally had to stop working because she was hospitalized when someone who had touched a patient touched her. Just couldn't take the risk anymore.
The OP did not make it clear in his original post that he had listed allergies before being assigned - it appears that he mentioned them on his application. My father had allergies to many cleaning products, so would have had a hard time working with them. Not enough to be life threatening (but who knows what would have happened after repeated exposure) but enough to make his life miserable.
It appears that he didn't know that he would be exposed to one of his until after his assignment, so WDW terminating him due to allergies was a bad move on their part. Glad to see that they found a different spot for him.