This seems like a noble effort, but Khan seems like the type of guy who likes to be left alone, contributing to the world as best he can. Spending time at TED would just slow him down.
Edit: sorry if that sounded crabby. I haven't eaten lunch yet.
TED started off great but seems like it has gotten a little weird over the last few years. Not sure how to explain it - maybe it's because most of the talks feel like mental masturbation at this point - they make people feel good, but don't result in action. Or it could be the liberal slant (the subtext of some of the talks seems to be "this is why we deserve more government funding").
From listening to a few of Sal's videos on finance, he seems to be more of a free market capitalist guy which may not mesh well with that crowd. A lot of this is speculation though, so I could be wrong.