I believe Aaron was one of his housemates who Black accidentally doxed after his and Aragorn's falling out. Most people who knew him in person seem to agree that Aragorn really was his name. 'Aragon' is the name of several US towns and a river in Spain, as well as, of course, with a variant spelling, a character from a famous trilogy of books, so I don't see why it's so unbelievable that his parents really called him that. I doubt he's the only one in the US.