So...you can't shoot till you demand cash, and you can't make a decent demand more complex than "cash or die" without them stopping. If they don't stop you can't do anything because you've got to make a demand before you shoot, which you can't do because he won't stop.
Added to the difficulty, typing macros are deemed as "illegal mods" by the admins, so they're not the answer. It's also impossible to type and hold tab at the same time, in order to make demands while afterburning after a retreating trader.
You don't make things easy, do you?
I'd also like to point out there are no "corners" in freelancer, to ram a trader into. Space extend in all directions. What you're actually saying is that, if a tradeship has someone on it's tail and is cruise disrupted, it should consider itself caught, while it's cruise engines are down. That's putting an awful lot of responsibility on the shoulders of the trader, whilst a pirate has no means of dealing with a Trader that won't play along, particularly since taking action might lead to the aforementioned Trader getting out the ban-hammer you've just given them.
I've never killed a trader that wouldn't stop before making a financial demand, but I'll sure-as-hell fire as many warning shots down their throats as to make them see my point of view.
Incidentally, money is the only commodity mentioned here. Don't I have a right to demand cargo aswell?