Actually if you go to dock to the pirate base, and pirate spots you, tells you to stop and you dock anyway, you are violating the rules of roleplay and will probably be reported.
Also, if you trade lets say.. XY material from California, and you get killed in California for not paying, and you spawn from the base where you bought XY, if you dont want to be pirated, dont buy it again.
If you undock again with the full cargo hold, you're actively participating in activity in that system after your destruction and pirate should be able to do whatever he wants with you.
So don't find loopholes in the trade law, because they aren't there to protect traders, but enforce equality.