That is a fair comment; there were or are moves to try and remove the non-open parts of OpenSolaris more open.
So that we're not throwing brick bats at Sun, though, I suspect Sun might have wanted to open all of OpenSolaris but got stuck with a codebase where some of the licensing for it simply didn't allow them.
That, of course, is exactly the whole point of many open source advocates' message - if you use ANY source that has a restrictive license you can lock yourself in and end up not being able to open your source as much as you'd like to.
There are arguments about the CDDL versus the other open source or free licenses but that, I don't think, matters here. My point is that even if Sun wanted to make ALL of OpenSolaris free (eg. GPLv3 free) they couldn't have due to prior legal obligations.