You are correct, that is the NEC code, and without a doubt the most insanely dangerous thing in the code. Their rationale is that it prevents a ground loop when, in fact, it creates a ground loop that can backfeed your house ground and literally explode every electrical device within. Remember, there is nothing, absolutely nothing, to hinder or prevent a backfeed. The NEC is not immune to mumbo jumbo code but this one takes the cake. What would you rather have, a ground loop that dissipates through the earth before it reaches your house ground or a direct line feeding the full force of the strike directly to your house ground? Don't believe it? Come visit my next door neighbor, his grounded flag pole took a direct hit last year that backfed the house and took out every device in the house including the fridge, furnace, A/C, TV, cable boxes, and garage door openers. He thought he was being prudent by following the code. Any strike should be allowed to dissipate at the site of the strike, not force fed to 1, 2, 3, or more locations through an underground wire network (check the code, they want every outbuilding with electric to have an inter-connected ground). That's just insane. I'm not saying don't follow the code, but don't believe the mumbo jumbo that it will help to protect you because it won't. NEC may know something about electrical wiring but they know very little about dissipating lightning strikes.