Let's start with this: What was the actual code section for which you were cited? Was it VC 22400(a)?
22400. (a) No person shall drive upon a highway at such a slow speed as to impede or block the normal and reasonable movement of traffic unless the reduced speed is necessary for safe operation, because of a grade, or in compliance with law.
No person shall bring a vehicle to a complete stop upon a highway so as to impede or block the normal and reasonable movement of traffic unless the stop is necessary for safe operation or in compliance with law.
If you were stopped AT a barricade, I'm not sure impeding would be the right section to have cited, if that was, indeed, the section used. But, maybe ...
From the sound of it, the person you tried you speak with was an employee or volunteer with the police department or organization involved in the event blocking the road, correct? Understand that they are under no obligation to have an officer come speak with you. Were you trying to have an officer assist in turning you around or letting you pass through the barricade? If not, what was it you wanted to speak with an officer about?
As to the officer's conduct, as was previously mentioned by flyingron, the officer's conduct is a matter separate from the issue of the citation. If what you say happened is entirely true, it would seem quite egregious and unnecessary and almost certainly a violation of policy. You can begin by making a personnel complaint to the agency involved.

