You can't argue a position by linking to a Wikipedia article about a logical fallacy.
It cannot be unethical to rely on a freely given promise that the other side has derived substantial value from.
Red Hat received the entire basis of their business by virtue of their side of that promise they cannot and indeed haven't tried to withhold performance of their obligation in that regard.
Under what ethical theory do you propose that creating downstream distros is unethical? Is it likewise unethical for Ubuntu to exist? If your answer differs why?
[1]: https://en.wikipedia.org/wiki/Straw_man