Cutting out all eggs and dairy even is rather extreme. Isn't it important to have a balance? Sure, eating only meat isn't good for you (most people would agree) but don't you need some?
There are plenty of cases where balance is clearly the wrong answer. There's no magic balance point between smoking cigarettes and not. So it's understandable that one might think that balance is better it just isn't a blanket rule.
Eating some animal products is a middle ground between veganism and the standard American diet. But who dictated that veganism was at one end and the American diet was at the other? If you were born in India and raised in vegetarian Jainist culture, you might find the "balance" point to be somewhere more towards the vegan side. If you had never met a vegetarian, eating an occasional veggie might be the "balance". So this is sort of meaningless.
It should go without stating that the balance between some unethical action and doing that unethical action on a smaller scale doesn't make it ethical. The middle ground between stealing 10 cars and stealing no cars is stealing 5, but that doesn't automatically make it ok.