I agree!
Intent and results are two different things, though. The redhead may have intended what you said, which I agree he did, but his actions produced a much worse result. In other words, just because he's negligent doesn't absolve him from the horrible way he treats Chanyoung.
I personally am more upset with his negligence and poor excuse for friendship. He fucked with Chanyoung's life in the past and has chosen to do it again. He's a grown man and he needs to learn to think first, keep Chanyoung's name out of his mouth, and keep his goddamn hands to himself.
Since a lot of people are confused by what happened, let me try to explain.
The red head is stupid. By stupid, I mean very stupid. He doesn't think far in regard to the consequences of his actions. That said, he is not a bad person. He is just really that slow.
When he "betrayed" Chanyoung, he didn't realize how badly his action would hurt Chanyoung. He only realized it years later, so he came back wanting to apologize. He expected Chanyoung to still be upset at him.
What he didn't expect is that the incident traumatized Chanyoung, hence why Chanyoung apologized first. This infuriated the red head because he believed Chanyoung did nothing wrong. It was his karma and his apology to make. He hated that Chanyoung made him into the victim despite it was entirely his fault.
So the red head being an absolute dumbass, punched Chanyoung in an attempt to provoke Chanyoung to punch him back. He didn't want Chanyoung's apology. He wanted Chanyoung to stand on his ground and not apologize as Chanyoung did nothing wrong.
Hyunjin's injury is a complete accident, which happened very similarly to how Chanyoung accidentally hurt the red head. The red head has no intention of hurting Hyunjin. It was Chanyoung's own assumption that the read head wanted revenge, when it was the opposite.
Anyway, you are free to hate the red head, but if you do, at least hate him for the correct reason. I see way too many people who misinterpreted his intent and character.