Is “refusal to disperse” a crime? I can’t see how it should be. Interfering with a crime scene maybe, but the 1st Amendment should guarantee the right to protest. I am sure this has been tested before, most recently with all the 1% sit-ins etc. But many city mayors sided with the protestors for a long time, hoping the protest would wane which they mostly did... though the cities did eventually have to close some of the parks and disperse crowds under other pretexts (traffic, interference etc).
Failure to disperse can be a crime. Protests can be controlled/regulated by time, place, and manner of the protest. This has been the Repeated rule set by SCOTUS.