Your friend is confused. There are some inalienable rights, like safety, discretion and keeping the session consensual unless pre agreed not to.

So the sub has some rights. Nowhere on this list is the right to dictate the content of the session.

If there are conflicts starting from there it is just a case of incompatibility and no need to continue the partnership.

Cheers to Domina M. Her answer is so right I should reply to her in French smile