Playing devils advocate, I suppose they had to kill Kubecka and Barstow. If the whole point is to monopolize the waste hauling industry on Long Island, you can't let renegades like them buck the system and possibly inspire others independents to do the same. I remember reading their company lasted for as long as it did because it stayed small and was not seen as a significant threat to the cartel. I guess they eventually got big enough where they got noticed.