My point was that I don't see how a steering wheel is any better. If you have enough control to rotate a steering wheel, you have enough to manipulate a joystick. In some cases, the joystick seems like it would be better, because it requires less range of gross motion, and can be located wherever it needs to be for the user to reach it.
I'm not an amputee, so I don't actually know, I'm just speculating. Ultimately, my point was that it seems pointless to say you can't deviate from the one established control design because the change might not work for some small set of the population. You're just as likely to have a set for which the current system doesn't work and the change does. What's needed is flexibility.