Gintis has three points. The first is that coops are organizations within the market system. We don't seem to be able to think outside markets anymore. The second, which I think is more dubious is the Bowles/Gintis argument that coops tend to be poorly capitalized and thus cannot e.g. invest in R&D or capital intensive new ventures so tend to be hammered by better capitalized non-coops. And the third point, implicit, is that people have been advocating and pushing coops since Robert Owens if not before and yet they remain very much in the unusual oddity class.

I'm not particularly persuaded by his second point, but the 1st and 3rd are strong and the 3rd does bolster the 2cd.

The counter to these, which is something I find really absent from most economics, is that the dominant form of economic organization in the world, the big corporation, is a grotesque monstrosity. Galbraith seems to have thought about this some, but Gintis does not seem to understand how these bureaucratic firms operate.