I agree, let the gender ratio be closer to equal, let the girls live.
But then again, the female gender is the key to population growth, hence why he cynically would call it unintended consequences. An unequal male to female ratio would have a bigger effect on population growth than females outnumbering males. This is an ecological principle, but I feel that it does apply here as well.
If the next generation is of equal size but 40% female, the population declines if each girl has 2 kids because it doesn’t replace excess males. From a “population control” perspective, fewer girls results in population decline if even replacement level fertility is reached.