But they are making a decision based on their personal viewpoints. That surely is the very definition of moral relativism:
Relativism is the idea that views are relative to differences in perception and consideration. There are a variety of different interpretations of the concept. The major categories of relativism vary in their degree of scope and controversy. Moral relativism encompasses the differences in moral judgments among people and cultures
John Paul II:
there is a tendency to grant to the individual conscience the prerogative of independently determining the criteria of good and evil and then acting accordingly. Such an outlook is quite congenial to an individualist ethic, wherein each individual is faced with his own truth, different from the truth of others. Taken to its extreme consequences, this individualism leads to a denial of the very idea of human nature.
When freedom, out of a desire to emancipate itself from all forms of tradition and authority, shuts out even the most obvious evidence of an objective and universal truth, which is the foundation of personal and social life, then the person ends up by no longer taking as the sole and indisputable point of reference for his own choices the truth about good and evil, but only his subjective and changeable opinion or, indeed, his selfish interest and whim.