Or its because they have the right to assemble. Not saying cops are great or anything, but its absolutely a good thing they aren't shutting down events based on their opinion of the people who run the events.
Those protests need to be heavily armed. It sounds radical, but that’s the proven method to avoid violently getting busted up.
During the civil rights movement, peaceful protests were violently broken, but armed protests were politely watched from across the street. Because cops have zero qualms about violently busting up an unarmed crowd, but get really fucking sweaty when the protestors can shoot back. It’s why the Black Panthers got started; People noticed the trend, and a group formed to arm protestors and stop them from getting busted.
It was so effective that it led to Reagan and the NRA passing the most restrictive gun control law the country had ever seen. The Mulford Act was quickly drafted and passed by republicans, to criminalize armed protests. Because lawmakers saw the armed protestors on their front porch, and saw the cops entirely unwilling to stop it.
Ironically, the reason liberal protests get busted is because they’re peaceful. White power rallies are always heavily armed, but liberals have a moral aversion to firearms so they have left themselves open to abuse.