China has high hopes for selling their upcoming commercial jetliners in large numbers in the US (and the rest of the world). If the CAAC is seen as not playing ball with the rest of the world it could come back to bite them big time.
Airbus has to tread carefully on this as well - while they are relatively clean on certification at the moment - stuff happens. It's not a matter of if but when Airbus will find the need for a receptive FAA - having EASA refuse to bilateral with the FAA on the MAX-10 could easily come back to haunt them.
It's a big industry - it's too everybody's benefit if they play nice together.
BTW, I see where Delta is already lobbying for the MAX-10 to retain a common flightdeck - pointing out that a unique flight deck configuration will add to costs and reduce fleet commonality (Delta currently flies a large number of 737NG aircraft).
I can see an argument that since many operators will use both the MAX-10 as well as the MAX-8 and -9, having a completely different flight deck on the -10 would increase confusion and could easily hurt overall safety - not improve it.