I think they left out Traders in on purpose. They want to allow pirates using freighters and transports to be able to dock and then return to piracy.
I believe they are holding the right to waive it so they can punish people who try to abuse the exemption. Ala a gang of combat freighters harassing people they know they can't kill continually. You know, the people chase them to a dock and they dock. Only to go back and harass the people again. They aren't trading and they aren't pirating. They've no way to kill their victims, but they can harass them endlessly.