1) The hedge funds don't have to be "funds-of-funds", and
2) I can choose the hedge funds.
But I suspect Buffett wouldn't take that bet. He strikes me as someone who doesn't take bets without knowing pretty well in advance that he'll win.
It also sort of alters the claim from "hedge funds as an industry will beat the S&P 500 overall" to "elite hedge funds can consistently beat the S&P 500." But given that he is a fund manager, I have no idea what Seides was thinking trying to claim the former.