He can type, he occasionally does type, but in general the injuries he sustained as a POW — ones that make it impossible for him to raise his arms high enough to comb his hair — mean that small tasks make his shoulders ache, so he tries to avoid any repetitive exercise.

Again, it’s not that he can’t type, he just by habit avoids when he can repetitive exercise involving his arms. He does if he has to, as with handshaking or autographs.