Having a disability is not am excuses to suddenly act rude especially with family and friends. Don't tolerate it! He needs to understand that just because he's disabled now doesn't mean social interaction rules are different now. I know I might sound a bit too harsh, but trust me letting him get away with being bitter and having bad manners will do no good for him either. It's true that with sci we go through 7 circles of hell, but it's not an excuse to be bitter and rude. Being well mannered is a must imo especially when now you rely on 9ther people, sometimes strangers to do regular tasks. Nobody owes us anything. My advice - zero tolerance for bad attitude and general meanness, especially considering he's age.