Um... what the hell does she mean, people with missing arms and legs don't change themselves? Prosthetics? Therapy? Wheelchairs? The fact that they often have phantom limb sensations and pain because their mind needs to re-adjust to not having that limb there?
If you ask me, she's only proving the point more, not disproving it. People with missing limbs spend a hell of a lot of time and effort trying to restore their body to a point of functionality that resembles what it was before the limb loss as closely as possible. They very well do not just say "oh well, no point in bothering to try and fix this" and pretend it never happened.