Well, I was saying why cannibalism is an objectively bad idea, outside a starvation scenario where the dangers of not eating the dead outweighs the risks of illness.
In terms of resource waste, they could be used as fertiliser, but you have to be very careful about it to keep the risk of disease down - there's a good reason we've long burned or buried out dead, afterall.
And tossing them into the wild also has the risk of training local predators to eat people.
It is objectively wrong to eat anything that has ever been alive.
What makes it's objectively wrong? Unless you have an actual real-world cost, and given the claim, a rather big one at that, you're just making an arbitrary assertion.
I can construct another argument that I'm sure everybody will disagree with but be unable to refute: the life of an adult is more valuable and should be preferentially saved over the life of a very young child. Here's why: from a societal standpoint, the adult is worth more, and from a personal standpoint the adult will be aware of losing more. The adult is contributing usefully to society now and has already been trained/raised from childhood. Raising the child to adulthood requires a lot of resources that could be saved if you select the adult over the child. Similarly, the child has no idea what its future will be like; the adult has a future and knows exactly what it will lose if it dies.
All depends on the circumstances - in a crunch, the adult's skills and abilities are probably more conducive to the group's survival, while the child is generally a burden and takes more resources to train/retrain.
That adult will grow old/get sick/die sooner, however, so the child is needed to continue the population, and care for the current generation when they get old.
So, yeah, from an objective point of view the child is worth less, on the basis that they're more replaceable. Long term, however, you need children, and as they're naive and vulnerable, an imperative to protect them makes sense - otherwise too few children would make it to adulthood.