With that kind of control, they could just put a gun to anyone's head and ask them to start mining bitcoin and do it the way they want them to. It wouldn't have to depend on how many bitcoin miners are in China at the moment.
It's a lot easier to point a gun to someone's head and say "Switch your equipment over to the network pipe that we give you" rather than point a gun to someone's head and say "Build a datacenter, secure an extremely large source of power, buy a few thousand Bitcoin mining boards, hook them all up in this extremely technical way, and then switch it over to the network pipe we give you."
The gun in the head strategy works best when you're only asking your populace to do simple things. For complex, technical tasks, the usual response is "Oops, I can't concentrate while you've got a gun against my head", and then you can shoot them but that's not going to help your task get accomplished any quicker. (This is also why working conditions at say Google or Apple tend to be pretty good, and why Soviet scientists were treated relatively well even if the rest of the population wasn't.)
And exert that control in subtle ways. "We know you, we watch you. You can do what you are doing because we permit it. When we come asking for a favor you won't think twice"
You can't just ask a random person to mine Bitcoin (well you can't, it just won't do much). It needs to be someone who has the mining hardware. So how many miners there are (specifically, how much mining hardware there is) matters.
Yeah, I just found that statement so weird that I had to reply.
If I had to guess first and second are deliberate suicide and deliberate homicide. But I suspect there's a huge fall from those numbers to what is the third and presumably last rank.
