should stick to their principles and ideas and do whatever they think is right. However, I don't think it's particularly healthy to tell their children to keep it a secret.
I just read an article where the women had their own reasons to still be breast feeding after 2, however, one said she only fed the younger one in public and the older one was told it was something just between them and not for public. Another bilingual child was told to ask for feed in their non English language so that people wouldn't understand what he said.
I understand why they might do this but I can't think it's particularly good to ask young children to keep secrets like this and wondered whether they should be bolder with their choice rather than secretive.