The more usual idea with population control is that one married couple will have multiple children. If they have more than 2.1 on average then the population will expand.

This particular comment seemed to focus on the man impregnating more than one woman, while saying nothing about the total number of children born per capita.

I thought they might have been talking about access to mates as a scarce resource, but to be honest that's just a wild guess as it's not clear to me what they intended.