China controls over 50% of the btc hashrate meaning they can do a 51% attack on the bitcoin network or control which btc transactions are valid according to their liking correct?
I believe a bulk of the mining hashrate is as a result of mining pools; miners from all over the world concentrate their computing power to a single server to increase the chances of them getting the next block collectively. This does not mean the hashrate is controlled by China, miners can easily switch to pools from other nations.
Indeed, there is no monopoly from China on the hashrate of BTC. Since the ban, the bulk of mining to maintain the network coming out of China is somewhat something of the past, as miners have already started to relocate.
As for China manipulating BTC's consensus, well, that's not so easily achieved because despite the miners having been in China it doesn't mean miners knew exactly where each were located to forum such an organised attack. Plus, the penalties if found out are harsh and it would destroy any miner's equipment and trust for future mining participation, a risk not many are prepared to take.
I think the owners of the largest pools have been known pretty much forever and if they wanted they could coordinate an attack regardless of their location anyway. As for China dominating the network on purpose, I guess they would only do it with the intent to harm the network and thereby perhaps destroy it. As that is almost practically impossible I guess, and as China isn't interested in a strong network that might give their own citizens possibilities to hide capital and get it out of China without anyone noticing, they are just trying to support the network as least as possible and to lock up their citizens within their own borders by cracking down on access to foreign capital markets and technologies like Bitcoin.