While the .243Win or .243WSSM may not be the perfect choice for the beginning shooter, they certainly are perfectly feasible choices for the experienced hunter/shooter (i.e. they've handled more than a couple rifles in their life and taken more than ten shots at a target)

No, they're certainly not in the same realm as say a .30-06, nor even a .257Bobby, but you don't honestly need 2000ft.lbs. to kill a deer.

If he does his job and gets the bullet where it needs to go, there is absolutely nothing wrong with his choice.