Ask HN: How far does a confidentiality agreement go?

I recently parted with a startup after three years to do my own thing. I think it's good to look back before looking forward, so I wrote up a rather long post recapping my three years (mostly relating to my own personal growth, the things I'm good at and the things I didn't enjoy).

As a courtesy I sent it to the CEO to see if he had any objections, which he did. After editing some of the more obvious bits and making the data more vague, I sent it back. There's currently nothing in there that I wouldn't put on a resume (i.e. we used this tech and that tech or I implemented this practice and that practice). After two weeks of hearing nothing, HR responded that it was still chock full of confidential info, that they weren't willing to tell me what was confidential, and that they would be in touch if I posted it.

Is that just bullying? I believe in good faith that there's no actionable "proprietary information" in my post, but it seems like they're making a pretty overt threat. Any advice?