If you knew anything about either character, then you would no that there isn't a chance in hell that they'd be holding hands at that point. Squall avoids any sort of emotional contact at all, including "comforting" people, whenever possible. And Irvine tries his best to seem like a cool dude who is always in control. Sure, he's scared stiff, but he doesn't show it on the outside, until he gets up to the clock tower. Notice that when they get up there and start freaking out, Squall isn't thinking "Oh, great. Not again", or anything like that. He is at a total loss about what to do. Had he comforted Irvine before, then he would no what to do to comfort him again, and would start with hand holding at acting as a reassuring presence rather than starting by yelling at him to fire, which is what he does.