If the bag was oversized then perhaps he should check it. If it wasn't then he had the right to show them it would fit. I've taken a duffle bag on the plane that looks too big but it's usually half full and compressible. I've only been asked one time to check the bag and I would always show them that it's not full. Perhaps I only took up 1 minute of everyones time...But if I know I'm right and they're wrong then I don't have a problem arguing. Historically the bag handlers show peoples belonging no respect and usually people who carry-on have either breakable things or something nice (in this case a nice bag) that they don't want destroyed. I believe people have this notion that the airlines are some authority in every respect but the reality is that everyone on that plane is a paying customer and if the airline is wrong then they have to be corrected (even if that means taking up other passengers time) He has the right as a paying customer to hold up the line if he has a legitimate reason. Like I said, ever since TSA started treating people like terrorist, the airlines has been able to treat passengers similarly and what's sad is that most passengers just put up with it.