The little coda about active management makes more sense if you read him religiously, because this is a schtick of his. Passive management helps most investors. But the market as an entity benefits from active management, because active management makes prices more accurate. This despite the fact that for the most part, contributing to the accuracy of prices comes at the expense of the actively-managed funds.
So without active management, the passive funds would perform more poorly, because their prices wouldn't benefit from the corrections of people trading into them to profit from mispricing.