Sounds like a feature phone would be a much better fit for him than a smartphone. Maybe pick out 2-3 to look at and have him choose one. Bonus is they're much cheaper.
Most feature phones available right now are pretty much the same, and they rely on rocker buttons and arrow keys for navigation, which he can't or won't pick up.
Right now he has a Nokia feature phone (which has virtually the same user experience as his older off-brand feature phone), and even that is too complicated for him to properly learn how to use.
