... I never said they did. On the contrary, I suggested they'd be adopting an off-handed pro-Allied policy. Japan and China are naturally going to be on opposite sides, so if Japan is in the Axis and an enemy of the British China is naturally going to be seen by London as "The Enemy of my Enemy" and, like Stalin provided with some strategic aid to help save British lives by sucking up Axis resources even if Churchill didn't particularly well like Chiang's regime personally.
As for the Manchukuo "Crisis", that was an overblown response on Stalin's part: legal scholars around the world, even as far away as Africa, readily accepted the validity of the arguement that Puyi was the legal heir of the traditional Manchu regions that had dominated over, but never legally subsumed under, China proper, making any Chinese claims outside the mutual dynastic connection unsubstantiated. As for Gwóngdūng and Mongolia, they were both had the legitimacy of internationally overseen referendums and have proven to be successful states for their non-Han majorities. Besides, once Hitler was gone I HIGHLY doubt the Soviets and British are going to be getting along in ANY case; not after how tenious the division of influence in Europe agreements were. Japanese presence provided a great deal of stability in what could have easily proven to be an unstable continent in the following years if Russia decided to support the violent guerrillas in Indonesia, Indochina, and India before the "soft landing" program of de-colonization and native reform could be implemented