There really isn't a consolidated "lore manual" like that in this franchise, although Fox purportedly kept one in-house for any projects being developed (more likely a list of "do-nots" than anything else).
You could certainly infer that from the film, but there's nothing to suggest that the predators have a homogenous culture like that. On the contrary, what we see in each of the movies seems to indicate quite a diversity it appearance and customs, etc.
Maybe this particular clan plays things that way, while others do their own thing, just like hunting clubs or sporting codes among humans.