That is trivial. It depends on the degree. A subjectivist is not the one who is not capable of being objective, and an objectivist is not the one who is not capable of being subjective.
Subjectivity is the epitome of what belongs to a subject. More extremely said: Subjectivity means that everything depends on the subject. Subjectivism teaches the universal subjectivity of the intellectual truth as well as the moral and aesthetic values and denies the absolute validity.
Objectivity is just the opposite of subjectivity. More extremely said: Objectivity means the lack of a subject. Objectivism teaches the universal objectivity as well as the neutrality, the practicality, also the capability of observing or/and representing objectively.
So, for example, if someone denies the absolute validity, then it does not mean that this one is not capable of observing or/and representing objectively. But it means that this one does not believe in an objective world in the sense that the objective world determines everything, even all subjects. A subjectivist believes in the theory that the subject determines the objects, even the whole world.
Subjectivity and objectivity are theoretical, spiritual, intellectual attitudes towards the determination of the world and the hotly favored answer to the question of the determination of the world.
The extreme form of subjectivism leads to solipsism in a logical sense, to egoism in an ethical sense.