Having them under Challenger will basically killed the game. They had to start big and separate to the scene right away
Remember that the game they have to beat, is not CS but Crossfire
having China to start in a small Challenger for without clear path vs a Complete National-level ecosystem (wrapped under a $1M franchising league) that CS has failed to matched local viewership against CF [and yes there is more people watching Comp CF than Comp CS in China], will spoke GG for VAL in China before it even began.
In a simpler explanation: Tencent and that's all the reason
Have you seen any Tencent-owned scene that China was small, none. Even the lowest (Clash series of mobile games) they still has it as separate spot
Have no guaranteed spots for them competitive = might just better skipping China market or see how Asian CS looks like atm.