It's ok for China to risk asset freezes, because there are more American assets in China than Chinese assets in America. Just like Russia is going to keep all those leased western planes that are stranded in Russia and probably many other western assets. In both world wars the US seized German private assets including patents. So as long as you are prepared for a total decoupling, you can keep all the publicly and privately owned foreign assets on your soil.
Of course it would be even smarter to borrow a lot of money from western banks before starting a war, then use the money to buy commodities and if there are any sanctions, default on the debt. That would cause a financial crisis for the affected banks and drive up inflation in the outside world because of higher commodity prices.