Iruka probably knows a lot of stuff Naruto doesn't. I mean, Naruto only learned about elemental chakra "recently". He still doesn't know about light and dark recombination or whatever.

I'm sure Iruka knows all about it, even if he can only do crappy techniques with it. If Naruto wanted to, he could probably do a lot of "book learning" from Iruka. Iruka probably couldn't teach him any techniques, but Kakashi isn't teaching any techniques either -- he taught Naruto a training method and told Naruto to go wild on a leaf.

On the other hand, who cares?