It's not strange behavior. It's just that wealthy, white people are discovering what poor people and minorities have known for a long time: the police are not their friend, are not accountable to them, and are prone to violent overreaction.
That's not true of every country though, it's certainly not the case in the UK. Here the police do act as your friends, they make a lot of effort to talk to the general public, both on the beat and at events. Certainly every encounter I've had with the police has been positive, even when I've been in the wrong (speeding or whatever). Police can be your friend, they can be accountable and they certainly don't need to be prone to violent outbursts.
The basic upshot of this story is to keep your contact with the Police brief, friendly and say no more than you need to.
The Police have been doing this to black people, gay people and other minorities for years, it's actually quite ironic that the Stonewall riots happened in San Fran too.
All that's happened this time is a well off, straight, white chap has realised just how hard life gets when you're treated as a minority.
I hope he gets his day in court and if the story is true they will sort the copper out and pay some compensation to him.
Something like "Sir, I'm going to need you to move to the other side of the street while we ascertain the situation." may work better than "Move to the other side of the street.".
But some of it is unavoidable. Americans seem to live with a siege mentality that I found uncommon in other developed nations (except the UK to a lesser degree). The police reflect this mentality with a constant fear that the people they're talking to will resort to violence. Of course, it is somewhat justified in their case because of the relative lack of safety in American cities in comparison to other developed nations (a homicide rate comparable to India, for instance).
[0] http://en.wikipedia.org/wiki/File:Chicago_violent_crime_map_...
Um, can you give a source on that? I rather doubt it's true, but probably depends on what you mean by "most dangerous". (And also perhaps "developed").
Here's an article titled "Violent crime worse in Britain than in US": http://www.dailymail.co.uk/news/article-25671/Violent-crime-...
Or here's PolitiFact:
> For England and Wales, we added together three crime categories: "violence against the person, with injury," "most serious sexual crime," and "robbery." This produced a rate of 775 violent crimes per 100,000 people.
> For the United States, we used the FBI’s four standard categories for violent crime that Bier cited. We came up with a rate of 383 violent crimes per 100,000 people.
[Source: http://www.politifact.com/truth-o-meter/statements/2013/jun/... ]
Already you can see that adding up those categories doesn't make sense as some will overlap (in particular violence and the other two).
That's an opinion claiming to be a fact.
Good engagement with citizens? The power is the draw to the position, not the responsibility that comes with it. Take away the power from the job, and see how many superheroes exist in the world.