Right handers tend to process language in their right hemisphere, and left handers in their left, probably because so much room is taken up in the other hemisphere - processing and integrating motor skills. Losing your dominant hand could have some pretty profound neurological effects. If this guy was relatively dextral (as opposed to sinistral) this change might not have made much difference, but if he was a sinistral who was effectively forced to become dextral, there could have been some relativiely large changes to his neurological condition; there are many differences between dextrals and sinistrals, more than there are between right and left handed people, I'd say.
I don't really know how to relate this to personality, though. We don't even have much idea about the neurological basis of personality. Introversion and extroversion can be explained neurologically, as the sensitivity of the CNS, but these psychological concepts don't translate perfectly to those in MBTI, and all the other dichotomies are somewhat fuzzy.
/Ti slave
