It would be extremely dumb for them to do it. consider they are creating tremendous value out of both the mining and the sales / development of mining equipment.
You probably don't know how communism (aka statism) works.
They do such things for displays of power. They rule through terror.
China is not communist. They are totalitarian capitalist and their most important priority is money. Also, they don't have to show power to the Chinese people, the Chinese people are quite clear about it. They are very well planned and sharp and they will cut off Bitcoin if they are not able to control it. They allow ANYTHING as long as it is controlled by them.