I think their point was that the public perception of Mother Teresa's altruism is a myth created by a media campaign. That does not necessarily mean that she did not behave altruistically at times or that altruism itself is a myth, but that the person the public imagines never really lived. They point out her flaws and mistakes and unwillingness to help when she had the means to do so, so she's much like any other person who tries to do good.