There's a huge difference between "we're sorry for our offensive behavior" and "we're sorry you were offended by our behavior." The first admits you've done so

There's a huge difference between "we're sorry for our offensive behavior" and "we're sorry you were offended by our behavior." The first admits you've done something legitimately wrong; the second only says that others were offended, perhaps illegitimately, and that wasn't your intent. The first is sorry for the action; the second, the reaction. In this particular case, all they have to do is say "We're sorry - we were being sexist. We've removed the sexist language and we won't do it again." If they want to clarify, they could say they were being unthinkingly, not deliberately sexist, which is almost surely the case.