Just because there are radical sects of the BLM movement does not mean that they're not going after a legitimate problem and that there aren't reasonable people working with them.
People like to romanticize the Civil Rights Movement as some kind of extremely peaceful series of marches down city streets, but there was plenty of disruptive protests and violence. When people are concerned enough about a problem in society, they're willing to make headlines and piss people off in the process of fixing it. And then sometimes when we look back in history, we're pretty glad they did it.
That being said, I don't think that this specific instance of disruptive protest was productive.