You piqued my interest when you posted this so being a MAAC member here in Canada I checked with our organization. We also do not have a discount for the disabled or vets so I asked someone who is in the know why not. Discounts are not offered because the concern is that every special interest group could make a case for their discount as well. Instead the concentration is on accommodating the disabled with proper facilities to enable them to participate in the hobby. In Canada we have a Disability Awareness Committee that advises the board on the best way to accommodate those with disabilities. I believe those that serve on that board have disabilities. Does the AMA have a similar committee? It might be worthwhile to get one started if not and if it does it would be worth contacting them with your questions.
Dennis