He's practically portrayed and semi-psychotic. He apparently assaulted Telford because "he was asking for it", he denied Rush water and then threatened to shoot him on that one planet and in this episode, he practically acts threateningly towards his new commander.
He comes to Camille Wray in her quarters, stands in front of her, looks at her with that semi-psychotic look of his, then speaks in quasi-threatening manner about how she suspected him of being the killer. I mean, why would he even discuss that with her? Then he just stood there, clearly trying to intimidate her and when she asked him to step aside, he did and then told her "I'm not going anywhere".
Clearly there's something wrong with Young and Scott, who seem to think the world of him. OK, so maybe he's good at shoot things. But I'm with Wray on this one. I'd have him as my prime suspect too if someone ended up dead anywhere near him. He's got some aggression issues and it might just be a matter of time before he actually kills someone.
I can understand Young sympathizing with his quasi-psychosis. But Scott? What, they're friends so he'll overlook his macho overzealous assaults and death threats?