I think it makes more sense if someone thinks "Gen AI is just NVIDIA - and if china has Gen AI, then they must have their own NVIDIA" so they sell.
But it makes the most sense if someone thinks "Headlines link US lead in Gen AI and NVIDIA, bad headlines for Gen AI must mean bad news for NVIDIA".
And the theoretically ultimate market analysis guru probably thinks "Everyone is wrong about Gen AI and NVIDIA being intimately linked, but that will make them sell regarding this news, so I must also sell and buy back at bottom"