Under 'arrest' only means that you are placed in handcuffs while the officer does further investigation. It doesn't mean there are any charges yet.
Why did the cop escalate it to that point? There was no justification for it.
Well... we don't know, do we ?
Perhaps the man was lying. Maybe that's why he resisted arrest.
If it turns out that the officer was too inexperienced (or ignorant) and the dealer's tag was valid and legal, then I agree with you and others on this thread that the cop has a problem.
However, we have only heard one side of the story. I can't hear what the man is saying to the officer, nor what the officer is saying to the man, before the struggle begins. This article only contains the WORDS of the Old man, and for all we know he may be lying.
Were these dealer plates ? How long has he been using them? Was he using them illegitimately ?
It would be nice to hear the other side of the story, and more details about Mr. Vasquez, before blanketly assuming the officer had no justification for wanting to place the man in handcuffs.