It was the same with the Reopen protests - they were allowed, just stupid. Health authorities say the same thing here - a lot of people are going to get COVID-19 from the civil unrest going on now, and ideally they should be quarantining themselves for 2 weeks.
FWIW, I support the BLM movement but I'm not going to any protests, largely because of the prospect for COVID-19 infection. We've been avoiding seeing friends because of coronavirus; we're not going to stand shoulder to shoulder with shouting strangers right now, no matter how much we support the cause.
The claim that lockdowns are somehow invalid now just says that, since we have experienced some setbacks on epidemic controls, we must throw epidemic controls out the window. I'm not seeing the logical connection. If a medical patient misses a dose of medication, doctors don't stop treating the patient.
We couldn't stop protests from happening. We've tried gassing the protestors, yelling at them, shooting them, beating them, and pushing them around with cars and riot shields, and those control measures haven't been completely successful. We may also have some legal protections for this kind of activity, I think.
And if the plight of people who live in daily fear of being curb-stomped or killed by the police is the same as your desire for a haircut, either your haircuts are very expensive or your well-being is only worth $20.