It's not a given that a rooster would be present even in the wild. But you're correct that this involves human intervention to be certain no rooster is present. And thus the amount of unfertilized eggs is unnatural. If OP is against killing animals I suppose he should apply that approach also to eggs in this sense (plus because of other potentially harmful practices at chicken farms). So more so he should look at veganism than vegetarianism.I'm talking about the eggs that haven't been fertilized, a life that could be was lost by the practise of isolating roosters, the person in the tweet is directly contributing to that loss of life but claims to be doing it for the animals, he's either hypocritical or ignorant.