I agree with sunseeker - I think the worst thing for him would to be forgotton and ignored. He would hate that I imagine.
Just shut away without being able to see any newspapers discussing him, no internet, not able to get letters from weird people who might want to "befriend" him, - nothing to fuel his craving for publicity. I don't feel he should have visitors either, especially not women who would still fuel his ego.
Should be kept in a very boring place with basic comforts only, made to do a good days menial work to pay for his keep. If he refuses then bread and water. To have the chance to read in leisure time, and I suppose a chance of self improvement.
But I suppose we couldn't do that to him, as we would then be denying him his human rights!!!