It's a good question. The answer seems to me that they're equally at fault, first because they're the same as what they're attacking, but also because everyone who bullies feels that way. No one ever sees themselves as the aggressor, so if you make an exception for bullies of bullies, you end up with the status quo.

The solution is to be aware of our own aggression and contain it. That's a long, slow process. I'm sure there is still aggression in what I wrote as well.