For what it's worth, I was talking to a buddy not from Valve that has claimed that the discount on the indie games came solely out of Valve's share, meaning Valve didn't get a dime from this promo and it's all just money in the indies' pockets.
Take with a grain of sale, of course, as this is second hand second hand, but if true it makes this "Valve is abusing me for their own gain" argument funnier.
edit - leaving that typo in as it kind of makes my point funnier, too.