Roswell did try to give Tyson a chance. Second or third day, he tries to have a polite conversation with him and says something mildly offensive which makes Tyson fly off the handle.
Everyone deserves a second chance, but they have to actually be willing to own up to their mistakes. Tyson specifically makes a point of not apologizing for bullying them and refuses to until he's essentially forced into it. I get that he did what he had to to survive, but that doesn't stop him from acknowledging that he hurt people and trying to make amends with them. Not apologizing is 100% shitty behavior.
It seems Tyson's arc is about becoming a better person but for the first half of the month he was absolutely not there yet and I'd say Roswell's attitude towards him is justified 80% of the time.