Do you think fathers should have the right to 50/50 split custody from birth, even if mom is breastfeeding and the separation will likely affect her ability to do so long term?
No, but “the best parent” is both parents.
Children want and need (even if they aren’t conscious of it) the care, love, and guidance of both parents. A child should be reared in the joint physical and legal custody of both parents, as long as each parent is a fit parent.
Clearly, joint physical custody of a nursing baby is difficult, if not impossible, to exercise, nor may it necessarily be best for the child, but the point should be doing what reasonably and safely can be done to rear the child in the joint legal and physical custody of both parents.