Well, a couple of things need to be said here. First of all, DO NOT assume the announcers are giving you anything close to accurate information. I see things all the time about rules, calls and ways they expect the officials to work that are flat wrong, but they have to act like they know what they're talking about. Because an announcer gave an explanation of a play means nothing. I say that because it sounds like that's the case in your play -- that explanation makes no sense.
NFL rules regarding pylons are so strange I have no idea what they are. I've seen really strange rulings in the NFL.
For high school (and NCAA, I believe, although I make no claim to know that code that well) the pylon is out of bounds. It's also in the endzone. So if a ball touches the pylon it is in the endzone.
Most people think of the endzone as an area of the field. But as long as the player in possession is inbounds, the ball can be outside of those lines on the ground. Anywhere behind the goal line is in the endzone.
That seems odd, I know, and I'm not sure it makes sense in that explanation so let me illustrate. If a runner is inbounds and dives for the pylon and touches it, he has broken the plane of the goalline with the ball. TD. If he is running down the sideline and runs into the endzone while holding the ball out of bounds, it's still a TD, just like a receiver is in the endzone if kept a toe on the ground inbounds but fell over the sideline and caught the ball 5 feet beyond the sideline and then fell out. A pass like that could, conceivably, be thrown by a passer who has jumped over the sideline but not landed yet and the ball never flies over the field of play. (How amazing would that play be?)
If a receiver hits a pylon with his foot before landing inbounds, the pass would be incomplete. I'd love to know the real ruling in the game you were watching.