I'm actually with you. My initial reaction was "this guy's a dick," but as I also noted it really does read more like a fledgling, immature Clark who has a disdain for authority and he certainly does grow over the run. For what it's worth, Sam seemed to be trying to help at that point, but I get why Clark sassed him. That I find it distasteful to some degree overall fits that arc. I agree that it's nice to not see Clark just eat insults and have a bit of edge to him, I think that particular instance rubbed me the wrong way because I have family who have served (a grandfather in WWII and a few others across multiple generations). Superman insulting soldiers for not having his powers really does just make him look like a bully who happens to pick on other bullies; it feels like punching down. I realize that's possibly not the intent, but maybe it was. Either way, he grows out of it so I'm overall fine with it's inclusion. A young Superman is allowed some extra grit before he grows into proper form. Unlike Snyder's Man of Steel, I think Morrison stuck that landing far more gracefully.