There is no pull request for Khan Academy. I don't even see a bug tracker. Teachers and other involved people have tried to do everything else; it just doesn't get their attention.
The last time Khan posted a call to hire on HN, I reached out to them about a position as a curriculum developer. They're more interested in expanding their back-end currently, not improving their instruction.
No he didn't came from India. He is born in New Orleans, USA. But point holds, there is awful teachers all around the world, including USA, and a vast collection of good quality instruction videos is valuable.
I'm from Finland, which tops in PISA rankings and what I've read about the reasons behind our good PISA performance, one is that teachers profession is still valued here, we have quality applicants and thus good teachers compared to many other countries.
Based on that experience, I'd say that Sal Khan is definitely above an average as a teacher. Anecdotally I'd say he is a very good teacher, but that's debatable.