Ken, Salty is not involved with the TSX people. This thread started 3 years ago. And you're right that commercial trips are not allowed on the Main Whitney Trail. (They could descend the "
Easy Walk-off" Mountaineers Route though

)
I visited the
www.tsxchallenge.com website. I see they have added three-day Spring Break trips to Grand Canyon. NICE! I should take my daughter!