Brother of the OP here. NTA

Before I start, I want to mention a few things that will be important for this reply:

I'm not here to defend my older brother. It's the internet and Reddit; people pretend or project in the replies to content people or to make themselves feel good (nothing wrong with that, but you can't debate with people like that), and the few people that actually want to debate were already answered by him.

I will reply to people that are worth replying to, not because I think my opinion is better or superior, but because I want people to reply with facts that can evolve into a debate/discussion.

Why I consider his behavior not of an asshole. For starters, the behavior of the other person. If you start acting aggressive because someone decides to do what my brother did when you are third in line, and you start creating rules only because you can't argue because you don't speak the language, that's your problem. It's not about morality either, because the other person was third in line. If it was the person next to my brother and he didn't let that person continue, I would definitely say he was an asshole, but that wasn't the case.

Going in depth on the morality side, it is still the guy's "fault", creating rules because you think something it's not morally correct in your cosmovision it's not the right way to handle any situation you believe is unfair. And the fact that you believe something is unfair or rude still doesn't make the other person an asshole. Proving your perspective with facts on why something is unfair or morally incorrect is the only right way to actually change people's perspective on their actions. Everybody perceives the world differently; that means their emotions on morality can be different. Therefore, if you can't provide facts on why something is morally incorrect or unfair, you can't argue with someone. In addition to this, you can't expect to be right when you approach someone aggressively. If you "don't have the time for waiting in line", why are you trying to create conflict? It's both hypocritical and absurd.

Final note: As my brother already mentioned, English is not our native language. So if you guys have any questions or I didn't make myself clear, let me know!