Imagine if the project agreed to publish (release) the Symphony codebase. That would require months of up front work, but would also be an ongoing obligation. We would need to provide patches and do CVE reporting on discovered security flaws. We would need to track bugs. We would need to respond to user and developer queries. We would need to maintain the code and periodically come out with new releases.
We were certainly willing to do this, if the project wanted to make Symphony be the new base for the OpenOffice project. But after examining the code and lengthy discussions, the community decided against that path and decided on the "slow merge" approach, to take enhancements from Symphony and merge them into OpenOffice. That is fine. I can see the merit in that decision. It is less disruptive to users. It keeps us on the code base that more volunteers are familiar with, etc.
But once that decision was made, it no longer makes sense to release the Symphony code base, and take on those support obligations. To do so would be to have responsibilities to maintain and support two different code bases, Symphony and OpenOffice. Double the work. Who would want to do that? Remember, the point of the Symphony contribution was to end the Symphony fork and concentrate resources on a single project, not simply to maintain the fork to another venue.