OR: Actually you just have to visit him a few times. Usually nearing (but still prior to) the pivotal end-game path at the unknown planet, the trandoshans will begin harassing the rodian--you don't need to leave the station after the first time, just go to your ship and come back.
...Hope you have a pretty penny for the rare items!
We'll murder them all, amid laughter and merriment...except for the few we take home to experiment!
"I cant see S***! --YOU GO TO HELL!" --Tourettes guy