I lived in Ireland for a while and it's true we use "us" instead of "me" though it's not that common and his tone doesn't fit. His body language doesn't show as someone saying "Don't kiss us". If he was saying that he'd be saying it to get under Khabib's skin. Him turning away immediately just doesn't fit that statement. In my opinion he says "It's only business" but possibly in the context "Don't take shit seriously, it's only business" as opposed to "I'm sorry, it's only business". To me it sounds pretty clear he does say "It's only business" but it just doesn't sound like an apology to me, rather a matter of fact statement, it WAS only business to Conor.