Earlier quoted context omitted.
I don't think he's rejecting anything, just making a general point about investing in something with cashflow (a business, farmland) vs speculating in something that is only worth what others will pay for it (gold, commodities)
Did you follow the link? Buffet's recommendation comes with a long time horizon, and the asserion that he can predict stability: "Whether the currency a century from now is based on gold, seashells, shark teeth, or a piece of paper (as today), people will be willing to exchange a couple of minutes of their daily labor for a Coca-Cola or some See's peanut brittle." I think he's right about people, but in the statement…
He was making a general abstract point, not a specific prediction. That's just the way he talks, and maybe it could be confusing if you are not used to it, but that still what it is.
And btw, MidAmerican Energy, a Berkshire owned utility, is the biggest investor in wind power in the US and just bought huge solar power projects.