It’s just as wrong to do something negative to someone who they think is doing something wrong. It’s one thing if someone thinks someone is doing something wrong and they SPEAK to them, but it’s another thing to actually do a sin ourself in reaction. For example, I remember when someone I know got upset about people we know, and I was worried that their anger might hurt our parnassah and so i got angry at him. Looking back, I realize that was not the right thing because that probrably would only make things worse, like double jeopardy. The best thing would have been that i just pray to Hashem and trust that He continues to provide.
We shouldn’t sin inorder to fix a sin, there are better ways to do things