Pro-police forces WANT mayhem. It makes people watching on TV afraid of the protests, and it changes the subject away from the widespread peaceful opposition to racist police violence.
"Comments should get more thoughtful and substantive, not less, as a topic gets more divisive."
"Eschew flamebait."
If you consider the rest of this page, you'll notice that most of the commenters support the protests (though of course they are divided, just as people at large are divided) and doing so without breaking the site guidelines. It's actually a surprisingly not bad discussion—at least relative to the extremeness of what's going on right now.