You miss the point. Releasing code is not about what IBM thinks. It is about what the project, working openly and transparently, thinks. The process of reviewing a new code base is not trivial, but it is worthwhile.
For example, when we reviewed the OOo code contributed by Oracle, we founds some errors and had to get them corrected with an amended SGA. Without our careful review, consumers of Apache OpenOffice, including LibreOffice, would have been worse off. For example, it would have introduced serious flaws into their rebasing of LO on AOO, and their subsequent license change to MPL, issues that could have caused them or their users trouble latter. So LibreOffice is already benefiting from our hard work in reviewing contributions. I'm certain they will continue to benefit in the future as well
If LibreOffice is interested in Symphony code (and they should be, lest they fall behind) then they should also want to see it carefully reviewed and brought into released form. That is in their best interest as well.