Yes they can. I don’t see why they’d want to though.
I would do it in a survival situation. But I'm thinking the circumstances that would make it reasonable are very improbable if not outright mutually exclusive. It would have to involve long range space travel with some emergencies.
Breastfeeding can burn a lot of calories anyhow. That’s why breastfeeding mothers lose weight faster than moms who use a bottle. I’d imagine that would cancel out the calories you get from the milk
A long range space mission where spacenigger pirates board and steal all the women and kill all the men. You and your team of three other men were away on a science mission taking samples from a planet surface. When you return you find everyone dead or gone. Most of the supplies were stolen except for eggs and bacon which the spaceniggers find revolting. Some infants, the future colonizers, were also left behind by the spaceniggers. Luckily your supply of progesterone was safe aboard your science vessel and you and your men can now convert the bacon and eggs into breast milk for the infants, saving the mission. Your species survived thanks to the chest feeding ace up your sleeve.
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