The important part of that decision was:
A police officer may not seize an unarmed, nondangerous suspect by shooting him dead...however...Where the officer has probable cause to believe that the suspect poses a threat of serious physical harm, either to the officer or to others, it is not constitutionally unreasonable to prevent escape by using deadly force.
This does not mean that every fleeing person can be shot. It means that if the officer feels that there is an immediate threat to himself or others, he can kill a fleeing suspect. That's hard case to make when the only thing you have is the car matched the description and two of three "suspects" ran. That, and the rather big caveat that these suspects weren't involved in the incident the officers were responding to. That, and the officer who shot had been sworn in less than 24-hours earlier. He was a cop for less than a day and this happened.
The standard isn't just that the offending officer can articulate a nonexistent threat, even a reasonable one. It must be one that a typical officer operating on a typical standard to care would have fired. And I think you'll find plenty of people who think he fired early, as the facts clearly support he did.
