CNN insists that recent riots in Kenosha and Minneapolis were mostly peaceful. This might have worked on radio. On TV, not so much. Possibly the term has been redefined by CNN. Could be. In the CNN world boys are girls, girls are boys, and Biden has his shit together!

I guess if one buys off on the CNN characterization that looting, burning and rock throwing are mostly peaceful activities, then what follows is also true.

This example of wife beating was mostly peaceful. She only has one black eye, no split lip and no bruising apparent on her arms.
Michael Brown is shown here committing a mostly peaceful robbery.
Here is Bobby Kennedy circling the drain. Sirhan Sirhan committed a mostly peaceful assassination. In a room stuffed with people, he only shot one person.
Here are two sexual predators and serial rapists. They didn’t use a knife or gun to commit their crimes, therefore they were mostly peaceful.
The ultimate in mostly peaceful. The inspiration for ANTIFA. During WWII Adolph Hitler never personally hurt anybody. His dogs liked him.

I hope I was able to put mostly peaceful into an usable context.

George Orwell