Exactly this.

If you were the CA, rather than spending the time and energy to post on another carrier’s thread because you were so offended, how about exercising some of that CA leadership with which you were entrusted and give the lad a proper explanation of the etiqutte expected of jumpseaters.

A gentle explanation of professional expectations would have resulted in some embarrassment on his part, but would have been far more efective than the big nothing you have achieved here.

He was wrong. But you were more so, because you let the opportunity to make a difference slip by.