Re: "why buyers beyond the middle kingdom would consider its offerings"
And I do not see China as winning this 'cloud war' just for one reason: trust-worthiness.
Yes, the US govt can legally look into your data if you house it in a US datacenter - but the reasons to do so still need to have some sort of legality, which with legal counsel can be contested / appealed.
China, on the other hand, does not concern itself with such trivialities. You can be in trouble for any banality.
Why subject yourself to that sort of additional stress of disruption?