Erm, Oracle is literally selling repackaged RHEL; they don't need to contribute anything back to Red Hat. They would if they wanted to replace stuff with their own closed-source forks, but that would be completely unpractical for reasons not related to licensing (see how Oracle's closed source ZFS become irrelevant compared to the Open Source ZFS).

As for Audacity: its owners couldn't do that without closing their fork, which would mean splitting off with the developer community and becoming irrelevant.