He shouldn't even need a reason. "I don't want a smartphone" should be sufficient and should not lock one out of commerce, events, and other cultural experiences.

When I run into this (most recently at a hospital), I tell them "The court doesn't allow me to have a smart phone because I'm a hazard to national security.†"

When they argue (very rarely), I tell them "Take it up with judge Kelso in the 225th District Court. He's in the phone book." That's usually enough for them to break out the backup non-smartphone plan. In my experience, there's always another way, but they're just too lazy to do it.

† Absolutely a lie, but I really don't GAF.

My man, they just think you’re crazy