I already said they can barely function on their own lol. Honestly every supernova crew is fodder besides Luffy's so that's not something special to Law. The point I was making is that he's connected to them as much as Luffy is to his own. Law isn't going to abandon them, especially since they have no home to go to like the Sun pirates did.
The gag is just an evolution of Luffy not understanding how alliances work. These jokes were made since Punk Hazard and Luffy flat out calls him a nakama in one gag
scene in Dressrosa. I don't think its meant to be taken seriously given that there's gag scenes of Luffy asking a dead tree to join his crew and gags around people not following his orders too. It's not unique to just Law.
I never said they were rivals. They're portrayed to be the leaders of the next pirate era and Law can't exactly be a leader under one of their flags.