If you dont't tell us what the thing in his hold was... its kinda hard to tell who was being a jerk here.
If someone has 5k of cardamine in his hold nad he says "you can't see it because I have special smuggling gear" he is the jerk.
If someone has 3 units of cardamine and he says its three doses for personal use and you say "no its not three doses its 3 tons" then you are being the jerk.
If someone has 4100 slaves in his luxury liner and says " they are vip passengers not slaves and you cant prove me wrong in RP" he is being a jerk.
If he has 2 slaves among 4098 other passengeners and says they are the opressed husband of a housedragon wife and the geisha of a kusari official and you say "no they arent they are slaves with slave colars who are clapped in chains in your hold and thats why Ill blow up your ship now" then you are being the jerk.
If someone has a wilde iff and wilde id and nomad weapons and says "you cant know Im a wilde", then he is a jerk.
If someone has one nomad remains in his hold and he says he just cut them out of his son's english teachers's chest and was bringing them to the insinierator and you say "no! you are a nomad smuggler! gimme 2 mil fine or die" then you are being a jerk.
If he gets a pvp or cash advantage from the cargo and pretends its something different to slip by you, blow him up.
If you are going to hastle someone and make a thread over an insignificant amount of RP cargo which has no other function than what he wants it to be in RP, blow yourself up.