You are right.
Moreover, I don’t quite understand what the opposite would look like. While masculine nouns have only two forms for nominative, accusative, and genitive, feminine nouns have all three forms different:
mas. anim. mas. inanim. fem. nom. преподаватель учебник учительница acc. преподавателя учебник учительницу gen. преподавателя учебника учительницы
The word преподаватель being a masculine noun just doesn’t have that separate accusative form.