You just don't get it, yet again. Beowulf is meant to build supercomputers cheaply, using off the shelf boxes and free software. It's only advantage is that it is low cost, enabling budget-constrained universities and scientists to join the world of supercomputing.
China's military doesn't have to worry about cost, as it has enough money to buy whatever supercomputer it wants.
The software begun by NASA (MPI and PVM) is also only a small part of the software that can be used to run an efficient Beowulf. Software written by others, including (oh my god!) foreigners, is most often used in making a Beowulf these days.
BTW, one of the reasons Linux is so popular for supercomputing is that you can change it to fit your particular supercomputing need. A usual Beowulf requires that you patch some processor, networking and memory functions of the kernel. Try that with Windows.
Without free software, there would be no Beowulf, even for our own universities to use. A consequence of that is that anybody can make one. Of course it'll be pretty slow unless the builder can buy the high-speed interconnect hardware.
Something else to spin your head: the world's leading supercomputing program tweaker, who can make a program several times more efficient on a cluster, isn't American.
So, when are you going to stop using this evil software that gives all our secrets to the Chinese? If your using it at work (which I doubt since you don't know the basic security tools that come with a distro) puts dinner on the table, I can understand. But I think you can afford to avoid it for recreational use on principle.
Wow, your infatuation with the Chinese is incredible. Of course they have to worry about cost, just as the USSR did, in fact many believe the reason the USSR collapsed was they couldn't afford the cold war. But you'd rather just give tech to the Chinese. And of course the Iranians, Cubans, North Koreans, etc, anyone and everyone.