If you build the campaign to accommodate the character in the chair that's one thing, but if it disrupts the campaign for the sake of a single player the dungeon master may have to draw the line.
People with disabilities are usually quite aware that they need to plan ahead - they need to do that every day for everything else, and should not be springing this on you last-minute. You generally won't need to be suddenly confronted with a player that doesn't fit your module when you sit down at the table.
"...for the sake of a single player...."
"Jim wants to play a scholarly wizard, so I'm gonna need to make sure there are spellbooks and interesting things to be solved with magic..."
"Sally want to play an aggressive barbarian, so I have to expect them to threaten a lot of enemies, and get bored with talky scenes..."
"Joe... you're just a single player. I can't make allowances for you."
This is kind of the story of their lives. All the time.