that falls under "modification of a technique you already know"
Edit: that and the rasengan isn't a WIND technique its chakra technique that can have various nature transformations added to it, he isn't shown using any wind techniques outside of rasenshuriken which is what I'm getting at- he can't for example, blast wind out of his feet, thats not rasengan related.
he does this for ONE technique, that is far away from ATLA bending.
I had to think it through, and I wasn't sure if you were going to accept "well no one is lava user currently and we currently don't have any lava users as a character in the roleplay, so this isn't really important right now" as answer since its going to be a bit an unknown how it works due to clan secret nonsense anyways.