That's not ethical either.
If he wants to run a proprietary software, it's bad for him, but for no one
else.
Think of a friend of yours wants to do something bad for him and maybe
unethical (but only concerning him, so don't come along with cheating with a
wife or something like this) and he wants your help.
You would refuse it even after giving him the advice not to do so?
That's really bad.
You should show to the world, that free software breaks down walls between
people.
This is a sad example how things can go wrong.
If I could, I would advise him not to do it; but then I would help him of
course.
