Not only that, but it's a supreme act of cowardice to have enough energy to chastise the bully's victims for not being nice to them, but not have the courage or energy to tell someone to stop being a jackass.

They think the victim of the bullying is going to give them a pass, and behave according to the script of deference in their head, and have the nerve to be shocked when they don't. They know the bully is only going to either ignore them, cuss them out, or beat their ass, and the easiest thing for them to do is get in the face of the person being victimized and tell them to be nice.

It's also deeply narcissistic, because if they're not a bigot or homophobe, why are they upset at some stranger being called those words? Could it be they think those words apply to them too?