Humans are imbued with a sense of hatred and dislike for oppression in all its forms.
This is most obvious when someone wrongs another, but it can also show itself when the oppressed gives in to extremism in his reaction and becomes the oppressor himself.
When this counter-oppression is seen publicly, the general people will naturally hate the new oppressor though they may have supported him previously. This proves true even if the one being newly-oppressed is disliked by the general populace in the first place.
The relation between the two and the specific details of the situation have now been abstracted away. They no longer matter. The core principle becomes prominent in the mind of the people; that no human being deserves oppression. There is no situation that justifies oppression and they will seek to subdue and punish the new oppressor even if the one being oppressed is someone they actively dislike.
People generally understand the nature of proportionality and restraint, even if they support retributive justice. When the limits are exceeded, justice turns into oppression and the one seeking to right the wrong turns into a bully.
If one chooses to retaliate against a wrong done unto him, do not exceed the limits you are bound by. Once you do, you forfeit the moral advantage of retribution and become eligible for the hatred and blame of others.