That is simply not the case, as mentioned in the article no MTCR member is forced to not sell any missile technologies to a non MTCR member, this policy is only followed by the US, if we need any advance missile technologies we could easily acquire it from China or Turkey (like the SOM cruise missile we were speculating that we might buy from them).
and that is the same case with China, if they for some reason needed any advanced missile technologies, they can easily acquire it from Russia, MTCR is nothing more than a voluntary group, it doesn't hold power to force members to limit their missile technologies sale to members state only.