The long term result is the same regardless of who makes the chips but the real strategy is delaying China's ability to surpass the US. It takes a lot of time and money to essentially copy the entire infrastructure required to build an Nvidia GPU. Nvidia has enough demand as is.

China is a trading partner but there is still a serious catalyst for war in the form of the South China Sea. If we went to war with China in 5 years time, why would we sell them the tech they need to match our ability now? Let them figure it out on their own.