This is a terrifying scenario. I find it especially disturbing if it is true that local law enforcement arrived but did not act.
Yes and no.
The locals immediately required the demonstrators to keep moving as required, and as soon as the homeowner arrived and announced "trespassers leave", they required the thugs to leave.
However the thugs did NOT have the required local permit to assemble, so they could have been immediately arrested and required to leave, and were not.
This means the local police brass and politicians are corrupt, and the local cops were just keeping their own jobs safe.