Another area where there would be unusual levels of cell death would be in the basal forebrain, an area that produces acetylcholine. If you could do histology on the living brain, you would also find an abnormal number of neurofibrilary tangles and senile plaques. At least with neurofibrilary tangles, a relationship has been found between the number of tangles and the decline in memory performance suggesting that their presence directly interfere with memory. The receptive field for the foot may have overlapped that of the genitals before the injury. However, when the foot was intact, input from the foot may have inhibited the sensory consequences of this overlap.
Behavioral compensation is one option.
This is the easiest and least invasive approach. Neurogenesis from stem cells might be another option, at least down the road. These stem cells could divide and form new neurons that would hopefully integrate themselves with the surrounding, undamaged neurons and restore function. Also, you might tell him that new research on facilitating the growth of an individual's own stem cells is currently being conducted and there might soon be some new treatments that didn't involve fetal transplants.