Facebook is a free service. They are entitled to enforce their terms of service. If these women don't like the terms, they are free to go off and set up their own website.

Facebook is not banning pictures of breast feeding per se. They are banning pictures that show too much breast, according to their explicitly stated paramenters.

No one is preventing these women from breast feeding, or disparaging their right to do so. They can breast feed completely naked if they want, but let them set up their own website and pay and maintain it, rather than demand that Facebook support THEIR views.