I mean there's literally no end to it unless your stronger than everyone, it's smarter to kill the witnesses to at least buy you sometime, now that may be severe and harsh but even if he had simply thrown him out without hurting him at all this would still happen, simply put the ego of people who think they can throw their dick around because they think they're strong ( or someone in their family is ) is so huge any setback ends with revenge of some sort or another, I mean it happens nowadays to but in different ways mostly people who think they can buy people, granted you can kill people as easily in our world than theirs so we are force into do other means or simply suck it up, probably part of the reason he's fine with killing adding up both life's he "lived" this is the easiest option ( probably not long run but still )