K, I won't say you're wrong ... or that I disagree with you ... or, for that matter, anyone else in this thread. The NEC is so poorly written, with such bad grammar, that I'm not sure what it's trying to say.
As I read the references, it's saying "if you drill a hole more than 2 ft long through wood, pull a cable through the hole, and cap it with foam, you have to treat those wires as if they were in pipe."
That's a very long drill bit!
What I think they were trying to say was "If a wall cavity is more than 2 ft long, is packed with insulation, as well as sealed with foam, we want you to consider the cavity as if it were pipe." That sort of makes sense ... but that's not what the code says.
As I see it, this issue only arises immediately above, and below, a panel - and then, only if the panel is on an outside wall.
I once worked for a company that is very heavily involved in the code process. Their Personnel Director made it clear that they only were interesting in hiring engineers and accountants. "What good is an English degree?" was the comment made. (No comment on that example of poor grammar!
) Well, looking at our codes, I think there is a greater need than ever for code panels to include someone with a degree in English!