Anyway you take it to them, the ADA will probably try and fight to accommodate him.
But whom will that benefit? A possible legal battle for your squad? It's already a PITA to be a volunteer. If I had to go to court to defend the need for a quick response, I would. However, if I were forced by the long arm of the law to "work" under conditions that will only benefit a disabled EMT, rather than a patients life, or the community at large.. I'd quit. You may not see it that way, but it will cause problems. But you can't make people wait for an ambulance, so you don't offend one of your members. I'm all for disabled persons living freely, and doing as they please; but it stinks when people have to put themselves in a position that could possibly do harm for countless individuals. How many people would it affect if the service was sued by X organization that heard of the troubles if it went through ADA.. vs. how many if it was just one person walking away?
How would his disability affect his ability to perform other functions as an EMT? Not lifting, but bending, accessing a patient, kneeling to a patient, doing CPR, etc? Somethings cannot be avoided.