If you read the article you'll realise it's not an open and shut case.
Yes, a store has the right to ask people to leave if they are not customers and that is the policy. If they don't leave, they are technically trespassing and Police can be called. The police do have an obligation to deal with trespassers.
However, you have to ask yourself how many people pass through a Starbucks on a daily basis. How many sit for hours at tables without buying anything and surf their laptops.
Then you have to ask yourself how many times the police get called on the these people.
From my reading of the article, two calm men entered a Starbucks and indicated they were waiting for a third party to arrive. This happens all the time without 911 being called. In this case, the Manager decide to call 911. Why? I can't prove he was motivated by racist thoughts but it's pretty damn obvious that's exactly what happened. Same with the police. They had an obligation to attend the scene because (even though it was wrong) a 911 call had been placed. However, once on the scene and seeing two calm and law abiding men, they could have negotiated a peaceful end to the situation. In fact, the video captures the men offering to leave and the police not accepting the offer.
Again, I can't read the mind of the officers but it's pretty obvious that they wouldn't have rousted a pair of Brooks Brothers college boys named Chad and Winston in quite the same way.
The Manager of the Starbucks should be fired immediately. I would not want someone like that in charge of my store and Starbucks shouldn't either. The police officers need to be disciplined in proportion to the role each had in the incident.