Breeding is instinctive with birds & I doubt that a hen would lay, incubate, then kill chicks she is nesting, to obtain nutrients for its own consumption. I would be more inclined to think that something else was going on around the nest that had/has the hen and/or her mate nervous & upset.
Almost anything might upset a setting hen, loud noise, constant noise, predatory animals…dogs, cats, etc., construction, looking in the nest box or otherwise bothering the hen and her eggs, people trying to move/handle the eggs/chicks.
There is also the possibility that the parents are a mismatched pair, a young, unproven pair or an incompatible pair. Some birds are not compatible with each other and while they may produce eggs, there may not be harmony in the nest box.
I agree that any remaining chicks should be removed and hand raised.
Better to be safe than sorry IMO.
