What they object to is a woman pulling out a large, engorged breast in plain view of everyone and then shrieking "stop sexualizing me." Breasts are intrinsically sexual. That they have an equal intrinsic role in child rearing is beside the point that if a woman with decent or great breasts bares the public, for whatever reason, many won't like that.
Call it a double standard, but then women either get away with legally prohibited sexual acts or get them plead down far more often than men do. The "privilege" on sex issues before the law is overwhelmingly in favor of women.