PVP rules do not apply to the trader - pirate situation, so yes, you can cruise to get him.
Seriously traders, what part of zero speed don't you understand. When you're caught, you're caught.
The situation mentioned above is totally exceptional, pirate without a train dist? Ha.
Either way, my favorite ones are those that "stop" but continue to head towards the gate/lane or whatever.
After first "zero speed trader means kill your engines" I usually go "2mil!" because of the server rules that say I cannot destroy him unless I ask for the correct amount.
So it kinda craps my roleplay.