ABC wanted the split to take place. Amaury belived investors win either way. Doesn't feel like winning now, huh? Question now is who can be unprofitable longer before going bust.
So when BSzv started broadcasting different blocks, and kept minig that fork, they made the fork permanent. They went their own way by their actions. Probably unintentionally.
Actually BSV firked off by their choice. We dont know if it was intentional, or if there were just unaware of how blockchians work. They transmitted blocks with different transactions.