There is nothing to stop you, and you fulfill Kuylen's assignment by slaughtering the defenseless old Rodian that leads the Chattza clan's activities on Nar Shaddaa. If their vendetta against Kuylen was not resolved before, it has been now. They will not come after him after the wholesale massacre you have enacted against them in retaliation for their attempts.
Additionally, though you do not meet her, Kuylen informs you that Shareth the Hutt is very pleased with your work. It has leveled the playing field for her line of business.
But, most importantly, you have proven yourself to Kuylen. He agrees to take you on as a student, one of many.
"I have great plans for you, Galder," Kuylen says. "And also, an assignment. Are you familiar with the legend of Avalar?"