Chinese mining pools still control at least 70% of the Bitcoin hashrate. They still have the biggest Bitcoin pools over the last couple of years, so we can say that they are in control.
I believe you're being mistaken here as I can agree with "they control the mining pools" but the fact is not true if you say that they are in control of BTC too because many investors of different countries have bagged themselves great chunks of BTC during its doom and these countries have got very high % in terms of holding BTC against China alone and I believe Japan gives a fair competition to China in same regards.
However, I don't think that they are stupid enough to destroy Bitcoin. Even though there are reports that they government is cracking down or have thoughts of shutting down Bitcoin mining farms because it is hazardous to their environment. I doubt that they destroying it has cross their mind, so this is just probably a hearsay.
None of them gives a damn to environment or any such thing when it comes to making money over it and they've got many sophisticated ways to mine BTC by powering their miners through solar energy. None of us would think about destroying BTC if we are a country because it helps aid many financial issues (not at a country level but) in people's lives generally and it is making a lot of difference to them while also teaching them the importance of BTC as an asset and cryptonomics.