Of course he'd like it in Mariposa.
If they were serious about doing this, wouldn't El Portal make more sense? That location in Mariposa would be about a good 35 miles from the Arch Rock Entrance, and not "just outside" like the article claims. Isn't there already an NPS presence in El Portal?
I've heard of some NPS administrative headquarters or other administration well outside of park boundaries, but I don't get this one. Cedar Breaks NM has its HQ in Cedar City about a 24 mile drive. Lassen Volcanic NP has its HQ in a place called Mineral which has almost no population. Mt Rainier NP HQ is just outside the entrance in Ashford.
Strangely enough, Mariposa (his hometown) is a speck when it comes to his constituency. The vast majority of his constituents live in the Central Valley.