Having worked with Seattle a little bit, I have to say that there is some truth to the sentiments in the post you quoted. There seems to be a hopelessly idealistic pie-in-the-sky view of thugs and criminals in some U.S. cities, which is used to constrain law enforcement from doing their job effectively. Then, when things like this happen, there is shock and awe amongst the local contingent of bleeding hearts, and much pointing fingers at racism and social ills as the causal factors, when many of these rioters were probably economically privileged and white. Vancouver is Seattle+++ in terms of liberality.
For instance, the city of Seattle (city council plus mayor) does not allow its police force to use the term "gang," because they believe the term inappropriately labels impoverished minority youth. Except, Seattle has a major gang problem, and the city government has put major hindrances in the way of effective responses by local police. Is the problem solved or erased by denying it and attempting to sweep it under the rug? Of course not. When high profile incidents occur, then, the city reacts with horror and can't conceive of those kinds of things happening in their lovely community.
This is exactly why Seattle went sky high during the WTO riots a few years ago. It's almost as if the city leaders can't conceive of actual criminals who mean them, the city, and local residents harm. Seattle, Vancouver, and a number of additional cities in the northwest are also hotbeds of anarchist nutjobs. When they go beserk, everyone acts shocked. I find it rather humorous, tbh. Except, for people who are the victims of this sort of stuff, it isn't amusing, at all.
Denver and San Francisco are similar in this regard.