Even if they will ultimately survive, I hope both MC and the third brother learn to handle themselves better while dealing with influential people.
I mean, the Eastern Lord Mansion dude was definitely a cocky cunt but this whole mess wouldn't have happened if MC didn't open his mouth to criticize him for no reason and the other guy didn't make things worse by acting like a smug asshole and insulting and threatening the other guy till he stormed off. People died because both of them couldn't shut the fuck up.
If you are strong enough to deal with the consequences then go ahead and offend anyone you dislike, but they clearly aren't strong yet and hopefully this whole indicent will teach them to be careful even if the guy they insult doesn't look particularly powerful since he might have a few friends who are.