I think the people being uncomfortable with ML have something to do with how he manage the situation when someone isn't useful anymore... The word "new" the ML always says when talking about the MC to new people that show in the comic always put me on alert... "This is the NEW teacher" make me think there was a teacher before MC... What happened to him? Or maybe am just reading too much into the situation ╮(￣▽￣)╭
Reading both these comments makes me feel like the reason ML keeps people that are useful is probably because the environment he grew up in you needed to be useful to be able to live, cause so far he doesn’t seem like he has any bad intentions either, and his character seems very simple and straightforward, so he might find this normal.
I think he's just someone who expresses his emotions freely, he doesn't seem to hide what he's feeling at all. I think the only thing that's making people iffy about him is partly his appearance and that we have no background information about him, we're reading with the eyes of the MC. I really hope that what we learn about him isn't anything horrible and he isn't two faced but just has an intense and daunting aura.
My theory might be that he's a lab experiment or maybe part maggot/zombie? Maybe that's why his eyes have no colour and maybe that why his arms are black and he has the Frankenstein stitches in his neck (they could also simply just be tattoos too). Maybe the reason why the people are kinda tense around Guwon or rather not be around him is because they were forced to stay in the town by him but don't fight him because they can't beat him physically or that the alternative is living outside in all the chaos. Maybe the way people entered the town was different to how the MC entered which is why people don't really go out of their way to be around Guwon, the MC thanks him and is grateful which is why he's doesn't feel uncomfortable around Guwon (maybe a little tense) but maybe again everyone was forced into it/against their will. Or, I'm also seeing that everyone is really strict on the rules that Guwon has enforced so maybe that's part of it and they don't want to argue with him or "back talk" to him in fear of being kicked out, maybe that's why Guwon was acting weird with the MC when he mentioned that he was back talking to him. He could also just be really manipulative which I'm hoping is not the case but we'll see.
That's all :)