Porque é uma piada em andamento do lado de Tony para Thor. Ele usou isso como um apelido para Thor em <> Os Vingadores :
Tony: No hard feelings, Point Break, you got a mean swing.
Portanto, é apenas uma continuação dessa piada.
E você já deve saber o Point Break (1991), em que o personagem de Patrick Swayze tem cabelo dourado igualmente longo:
O que é pouco parecido com as travas douradas de Thor em
Este artigo do Screenrant identifica a referência aqui:
When Thor enters the Quinjet he has a hard time gaining access to its controls. The ship asks for voice recognition input and he uses many different names including, “Thor,” “Thor, Son of Odin,” “God of Thunder,” and “Strongest Avenger.” However, the name that ultimately gains him access is “Point Break.”
Point Break is the name Tony Stark gave Thor in the first Avengers film because of his resemblance to Patrick Swayze in the 1991 film, Point Break. In this surfer-robber ’90s movie, Swayze sports long luscious blonde hair, much like the God of Thunder’s flowing locks, and Stark is more than happy to point this out from time to time.
No wonder Thor says, “Damn you Stark” as soon as he gains access to the Quinjet.