Let us assume there is a character who cannot obtain a Force Rating (either through species limitations or any other factor) or be Force sensitive. Can a character who is incapable of having a Force Rating willingly forgo the "gift" of a Force Rating in order to buy into talent trees in a career that normally provides one?
Obviously they won't be able to take Force-based talents. But, to avoid conversations about motivation for doing so, let us assume there is reason enough for the player to want to develop trees for Force-based careers.