Personal opinion, but I like the cantilever mounts.
I do too on that style of optic.
If he's running a PA, here's a cheap and easy mount that would serve him well.
[ame=http://www.amazon.com/Cantilever-Mount-Aimpoint-Scope-Sight/dp/B002BUF8XG]Amazon.com: AR15 Cantilever Mount for Aimpoint Scope & Sight w/ RIS Rail Top: Sports & Outdoors[/ame]