Thanks for the chapter!
Granted killing the boss might bring a lot of attention to the city, but not killing him would've brought more. As soon as he got away that boss would've broken the deal and spread the word MC was there and injured. Either as some form of revenge or just to spite MC. Since it seems society is more of a might makes right belief it's likely all the boss' wrongdoings would be overlooked due to the information he gave although wouldn't put it past the guys coming after MC killing him for a perceived insult with intention to take control of territory or to avoid paying for the bounty.