I think it would be important for him to sit down and express his ultimate (or, as far down the road as possible) goal. If it is true musicianship and the ability to move easily from one instrument to another I would say start on the acoustic. It is more demanding in several areas, and has been mentioned, can be played anywhere at any time for short periods of time (important during those "build up the callouses" stage). However, if he truly wants to focus on the electric side with no real plans to cross over to an acoustic guitar, mandolin, banjo, etc, then start him with a nice electric and amplifier system. It will not be as painful to learn initially, and with a good set of headphones he will not make the household pet too miserable.
I would try to communicate to him (maybe a good salesman would help here) that the two instruments may LOOK similar, but in style and substance they are really two different animals. Many start with electrics and switch over to acoustics, that is for sure. However, I think the easier path is to start with an acoustic, and then add the electric. Skills learned on the acoustic are more easily transfered to the electric, but some less-than-exact techniques that work quite handily on the electric will have to be un-learned when the change is made to an acoustic.
Bottom line is what is going to float his boat. He may think girls dig the lead guitarist in a rock band, but does he understand the sweet nectar of a lovely little love ballad and a moonlit night with just the object of his affection as the audience for his acoustic??
Some dawgs weren't born yesterday, ya know.