I don't understand what you want to fight. You said you were "double parked" and got tagged for it. It's illegal to double park so whats' to fight?? I can't figure why people double park, most drivers find a legal place to park, even though they might have to walk. Usually when people double park they have someone else blocked in.
He wanted you in your car, so he could keep you in his sight, but not be threatened by you, should you have been be a "bad guy" Not easy for the cops to tell the good guys from the gun toting bad boys.
It's just a parking violation (in Calif.) so I would save your energy, as far as fighting the ticket. Just my .02 cents worth and you did ask