I just don't think having the most secure quantum cryptographic communication system is the type of technology they would gladly want to share with the rest of world. Sooner or later, the secret service (do they have one?) or military will be involved. Will we see another Cold War-ish information technology race?
You make it sound as if this selfishness and militaristic lean is specifically Chinese in nature and that other freedom-lovin', rainbow-kissin' nations engage in free and open exchange of knowledge with no military aspirations whatsoever. "Oh if only those poor misguided Chinese shared like the rest of us do we wouldn't have another cold-war." I mean I understand why you might be prejudiced to think that way because I presumably live in the same NATO bubble as you do, but this kind of "our values vs. their values" thinking is the exact Hollywood-like narrative that starts wars in the first place (and by that I'm not accusing only westerners of this, I'm pretty sure it happens in China too).
But while technology might be used for purposes of conflict, I think that the digital age also has the potential to break the barriers of distrust and xenophobia between people of different nations. It's sort of happening on a small scale already. You are able to have a conversation with a person in China (when their internet is not being blocked) and realize that they are not a DVD-copying, cat-eating, environment-hating communist that your society might suggest they are. Governments often use the lack of knowledge about different nations to justify going to war or blocking trade. Maybe with the new age of global digital awareness we will not have such an easy time cultivating distrust and hate. Or maybe it's gotten to the point where we all distrust and hate each other on an individual level.. in which case we're all fucked
What world do you live in?