They should all sue the Seattle Mayor, the city council, the governor, and the Democratic National Committee as well as any corporation that funded the Antifa creeps.
They likely have no legal grounds to do so.
However, you are exactly correct. It is the Leftist politicians who are allowing, and, in essence, promoting this behavior.
They are so far down the leftist rabbit-hole, they don't even realize one of the centers of Democrat power in the urban areas, has always been the city police departments.
Now, they are actively delegitimizing the police.
This will drive the police, and citizens desiring a peaceful existence, into the arms of the Republicans.