Fair point, but I dont think ideas are worthless at all. Given that he is not building startups to execute on these ideas (and alludes he probably won't be in the future), I thought it would make his case much more compelling if he did share. Maybe a few ideas... or just the headline idea without the detail.

I got into a bit of back-and-forth with him on the blog, but I did agree with his general thesis. FWIW, I think throwing out an idea on HN is not a terrible idea. The feedback and useful suggestions probably outweigh the risk, especially if you are already working on building the business (i.e. past the 'idea' stage).