The 270WSM or WBY isn't going to do a dang thing that the regular ole 270 cant already do.

As factory loaded in equal length barrels with 130 trophy bonded tipped bullets you are only going to gain about 5.5" in trajectory and 1.8" less wind drift at 500 yards.

If he wants a .270 magnum then I certainly won't try to talk him out of it but if he thinks that one of the .270 magnums is going to give him some kind of magical advantage in the field then he is dreaming.