Yeah, both of you have some of the blame for poor RP there. As a OSC ship captain, you should be more than willing to comply with a police officer's orders, no matter what ship they are flying.
Here's how I would have approached the situation if I were in your position.
1. Tell the police officer that any cardi onboard was brought onboard by the passengers, without the ship captain's knowledge.
2. Offer to talk to the passenger who brought the cardi, and ask him to dump it out the airlock.
3a. If the passenger chooses to dump it out, drop the cargo, apologize to the officer, and go on your merry way.
3b. If the passenger is not willing to leave the cardi, RP some burly security men throwing the spoiled rich brat out the airlock, along with the cardi. Then go to your cargo screen, dump the cardi and one passenger into space, and continue on, letting the police officer deal with the now-floating passenger.
Anyways, as a passenger liner, your first priority is the safety of your crew and your passengers. You should not even put yourself anywhere near a situation which would involve danger to your passengers.
I am curious as to why you were carrying neon in your hold though. Lux liners should not be moving that stuff around.