Something you wouldn't say in the same way to someone's face.
http://journal.dedasys.com/articles/2007/04/26/ideas-are-worthless
I also think some of his "startups are the future" thinking is naive in that it excludes many fields of endeavor where far more significant amounts of capital are necessary to get anything going.
But I wouldn't have any problems telling him the same thing to his face, over a beer. From what little I know of most people on this site, they all seem reasonable enough that I'd quite enjoy talking with them about a variety of things, even those we might not agree about.