Despite all the advantages of free software, often it is very useful to use a particular proprietary tool and often it is very useful to learn (and thus, teach) how to use a particular proprietary tool, and there's nothing unethical about doing that useful thing instead of refusing to do because it involves proprietary software. Some people would refuse to use proprietary software as a matter of principle, and that's
also a valid ethical choice, but it's not the
only ethical choice.
Calling an action unethical is a strong accusation. It's very rude to call an action or a person unethical unless the wrongness of that action goes way beyond merely not taking advantage of an opportunity to facilitate some ethical goal, calling it unethical implies some active wrongdoing instead of failing or refusing to take what you consider the most beneficial choice.
