ANSWER:
She is an ignorant student of knowledge that is misrepresenting Islam and tarnishing its reputation by her actions!
She needs to learn the basics of knowledge and to just imagine what the prophet salla Allahu alaihi wa sallam would have done in similar situations.
Of course giving salam to such people who are mahram and friends of her mother is highly recommended if not mandatory! This is not wasting time at all, rather it is part of her priorities.