Well, in fact he could move and talk. Damage in the spine wouldn't affect all his nervous system, at least not the parts he was shown using. Think of people with people with spine damage at waist height, they can move their arms and everything above the height of the damage.
Now, nothing else here makes sense. I don't know how he could re-atach his legs. I'd expect his body would try to close the massive open wounds so they won't make him bleed to death.