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.
Of a truth I really don't know what the Chinese government will stand to gain in all this attempt to strangulate the bitcoin apart from egocentric display if power, perhaps against its citizens. I have allowed my mind to wander if the Chinese are not daring the global economy with this action...It started with regulating ICOs to banning it, then banning bitcoin and now, mining? This isn't something the Chinese should be proud of.