Pedantic and nitpicking and quibbling.
By which you mean "I wrong but I'm never going to admit it", right?
Korean Gwonbeop was not extinct 100 years ago.
Well, yes. It was.
Also, I don't care if Byungin Yoon taught Chinese Quan Fa (Gwonbeop). It's a definite possibility. I accept it although my main belief is that he learned and taught Korean Gwonbeop. But Taekwondo topic is over. He taught Quan Fa. Over.
Nope. You're wrong. He taught Kung Fu, then he joined the unification movement and taught... yup.... that's right... Tae Kwon Do.
Which is primarily (almost exclusively) derived from.... Karate. Specifically Shotokan Karate.