whats wrong with a pirate transport who runs to a base, then goes after the cop has gone to go to another pirating spot in that system? If you couldn't stop the pirate before,, try to get a LF with you next time.
Otherwise, if its obvious the player is using a transport/frieghter, docking in your sight and comes back and keeps shooting you, then report him, as Revereand has said, if it is obvious they use it this way then the rule will be ignored as they are harming the purpose of the rule in case's like that.