I don't think FSF would disagree. As I said most parts are fully GPL compatible licenced. However, my comment was about the ideology/philosophical background.

> “Open source” is something different: it has a very different philosophy based on different values. Its practical definition is different too, but nearly all open source programs are in fact free. [0]

I would say that FreeBSD is the prototypical open source OS.

[0] https://www.gnu.org/philosophy/free-sw.html