??? Because it's not relevant, Mr.Nintendo. Unless you've got a disability neither is necessary for flying Index-thumb.
Well our club don't (and btw. I did NOT even teach most of them at this one).
Cobblers. They just aren't relaxed. Fly Nintendo if you want, though.
And I bet you're teaching him to fly the way you do.
As for a correlation between "mixing socially" and flying thumbs. It's the way people start when they try to learn on their own.
You forgot to answer this: "Thumbers convert to index-thumb but next to nobody tries to converts to the thumb way, explain that."