I don't think bibi is always derogatory
- Summer uses it affectionately in the note she left Nika (I think)
- William uses it when he says he loves Katie "bibi sister" (little sister)
So Nika is the bastard of some Wollust big shot, it would explain several oddities around Nika
There's the bit when Summer's playing basketball, she uses it to deride Nika as incompetent, Leia and William teasing Katie with the bibi dinosaur, because she's not grownup like them
so she gets the shitty toy. It's not 100% derrogatory, but it is very often used as a put down, to make someone ...small and less important. Willi will typically give Katie backhanded compliments, prasiing her while putting her down, so I think the context I'm suggesting is fine. Leia of course is using it to put her workers in their place, they're pawns, and she's the queen.
The thing about Nika is we don't know who his family is, and I suspect it'll be one of the longest kept secrets in Ocean's games, with HEAPS of red herrings and false trails. Ocean probably laughs himself silly about the theories we come up with to fill in the time between updates - if you've been on his discord, he plays with people's ideas, seeming to give support, but really trolling people with their own theories. He's not going to give that up for a while.