You're age isn't a factor / and it makes no difference to me. On my squads, I expect and enforce the shooting rules of etiquette ( even on very young kids ) / and on my squads, I don't have much tolerance for people that misbehave or do not show other shooters the same courtesy they deserve. This is all outlined pretty well in the rule books / and at most gun clubs.
Trap, Skeet, etc are supposed to be gentlemen's games / it isn't a place where anything goes. I don't have a problem with making allowances for new shooters / because they may not know - but hopefully one of the members or a range master will talk to them. On my squads, everybody should stop their converstation when other people are shooting / and there shouldn't be anyone in your peripheral vision moving (you and other shooters, should stand motionless when the person next to them is shooting - and that includes moving your gun - especially when the shooter next to you is shooting ). There shouldn't be anyone behind you disrupting your concentration / and no convesation should be loud enough behind you that you can hear it with earplugs or muffs on.
In my view the guy standing behind you was being rude. I wouldn't tolerate anyone on the field, standing behind me, unless it was a referee. I would quit shooting - and ask them to leave the field.
But that doesn't excuse your actions by tossing shells back their way either. That kind of behavior can get you removed from the field as well. If you're telling me you want to fuss with your ejectors - to make the guy behind you move back .... I will tell you to take a deep breath and think this whole thing thru / because you're very close to behaving improperly. Its not in your best interest / let alone messing up your concentration - to play games with a guy standing behind you. His rude behavior doesn't mean you can do whatever you want - sorry.
Some clubs have rules that say if a hull hits the ground / it belongs to them. If that is not the case at your club - you ought to be able to police up your own hulls when you're done. If someone else is picking up hulls, it would be polite for them to offer you, your hulls. But like I said, it is also rude to let your hulls lay on the ground for somebody else to have to pick them up when they cut the grass, etc.
My honest counsel to you - behave like you would if your parent, coach, your wife, girlfriend, ... - or any other person you respect - was standing there watching you shoot and compete. A Trap field is not a place for "hockey arena" behavior from spectators or especially shooters. There are days at my club when I am just not shooting well or taking my misses seriously / but it doesn't mean my behavior changes on the field or affects the other shooters around me. The guy standing behind you is a jerk - let the range master deal with him. Don't be a guy that goes to a tournament - and when other shooters find out your're there / noone will shoot on your squad.
We have a couple of guys like that in my area - they are very talented shooters - Master class / and if I get put on their squad because the rest of my buddies did not come ... I'll demand the shoot organizer move me to a different squad - and it better be at least two squads away from those guys / or I will forfeit my entry money and leave the club. I don't care if you win National Titles - please don't become one of those guys.
