In a few previous questions, I mentioned that I sometimes daven in a nursing home minyan.
This past Shabbat, the gabbai asked someone who is confined to a wheelchair to daven Musaph. There were other non-disabled people in the shul. I assume that since this person was a guest, the gabbai wanted to give him the honor.
The prayer is called Amidah because one should stand for it, if he can. Is a shul allowed to use someone who can't stand for amidah as a shat"z if there are others who can stand?