California Penal Code Section 402
402. (a) Every person who goes to the scene of an emergency, or stops at the scene of an emergency, for the purpose of viewing the scene or the activities of police officers, firefighters, emergency medical, or other emergency personnel, or military personnel coping with the emergency in the course of their duties during the time it is necessary for emergency vehicles or those personnel to be at the scene of the emergency or to be moving to or from the scene of the emergency for the purpose of protecting lives or property, unless it is part of the duties of that person s employment to view that scene or activities, and thereby impedes police officers, firefighters, emergency medical, or other emergency personnel or military personnel, in the performance of their duties in coping with the emergency, is guilty of a misdemeanor.
(b) Every person who knowingly resists or interferes with the lawful efforts of a lifeguard in the discharge or attempted discharge of an official duty in an emergency situation, when the person knows or reasonably should know that the lifeguard is engaged in the performance of his or her official duty, is guilty of a misdemeanor.
(c) For the purposes of this section, an emergency includes a condition or situation involving injury to persons, damage to property, or peril to the safety of persons or property, which results from a fire, an explosion, an airplane crash, flooding, windstorm damage, a railroad accident, a traffic accident, a power plant accident, a toxic chemical or biological spill, or any other natural or human-caused event.
Looks to me like the citation is a valid one - although YOU weren't on the scene, your drone was.
I've always had great success in defending against traffic violations by appearing in court myself, without representation. Usually the violation is thrown out, the rest of the time the fine is lowered considerably. Although you could retain an attorney, if I was in your position, I'd just request a hearing, plead my case that I did not knowingly enter a rescue operation and following police instruction as soon as I was made aware of the situation.
The other alternative would be to retain one of the attorneys that specializes in drone law. There are a few. It may be that it would only take a letter to the judge (not even an appearance) to get this dismissed.