I'm pretty sure AT&T does have strict requirements from Apple, and that this one retail employee just dropped the ball or has some (also understandable) distast

I'm pretty sure AT&T does have strict requirements from Apple, and that this one retail employee just dropped the ball or has some (also understandable) distaste for the iPhone-as-fetish-object ritual and is just choosing to opt out of it. A carrier's experience will always be inferior to an Apple Store experience. That's news to no one.