Chickens do not need to be crammed together in order to produce eggs, eggs are an incredible source of numerous nutrients, help with the bodies management of cholesterol, and getting eggs is also sustainable when not brought to mass production levels of crazy.
Red meat is an issue in large quantities. No one should be eating it on a daily basis for what it gives nutritionally. It can still be eaten, and does still have a lot to offer when it is not over consumed. Just like basically everything else one can eat.
The problem is scale and misinformation, not the food source itself.