Looks like this happened a little while ago. But really, it's unfortunately all too common.
In this case, it sounds like less than competent troopers were looking for a scapegoat they could blame for not finding their actual suspect. Generally, an obstruction charge technically has to be willful, not accidental (as in this case.) In fact, they had already made contact with public safety dispatch and were complying with their instructions.
The other disappointing pill to swallow is that the courts tend to side with the officer (also in this case), even when they are wrong.
The accusation was that the presence of another human in the area prevented the dog from tracking the suspect. Um... excuse me? The dog wasn't confused by the human officers on scene?
Really, if your trained dog is confused that easily, it's time to shoot the dog. (Not literally of course... but you get the sentiment.)
My suggestion is if you are targeted for unlawful arrest for 'obstructing/delaying', get a good lawyer to clear you of the charges, and once cleared, sue the district/officer for unlawful arrest.
I am pro law-enforcement, but also anti-abuse.