If you’re buying a Mature game, don’t bring younger siblings

[BenKenobi88]

Parokki said:
Why did he stay and argue for three hours? He could've just come back alone later after they've forgotten him or something.

 Maybe he thought his rights were in violation or something.

But of course...a store can deny a sale to anybody they want...

The brother was not a guardian, he's not allowed to buy a game for his little brother, that's store policy pretty much everywhere.  He should have said it's his money and he's allowed by normal rules to buy the game...the manager would have to agree.