If Jack wanted to imply that they had all been inside twiddling their thumbs, save for Pam, while he had been outside getting assaulted, and then get pissy when told otherwise, that was on him. No one had wanted this shit to happen, and Owen wasn't trying to become 'best friends' with anyone. He was trying to calm the guy down enough so that no one else got hurt, and Jack would rather say shit to piss the guy off even more - while Cecilia was physically restraining the guy - than recognize that. Simms seemed like a dick, yes and Owen didn't want to deal with this at all, but he certainly wasn't leaving Cecilia alone to do it. Weren't they supposed to handle this shit like adults rather than just "stow" away any potential problem?
Owen just didn't have the energy or patience to deal with arguing with Jack, so he said nothing as Jack and Pam left, his expression stoic. His own stance was tense when Cecilia moved away from Simms, and he was ready to throw down immediately, just as Cecilia was, if the guy tried to get violent again.
"There are good people here," Owen told Simms. "Including Jack. That's probably the first thing you need to know about this place, because everything else is probably going to sound crazy and impossible."