What is really deterring the Chinese from selling weapons to Russia is the Europeans not the Americans, the Chinese give a rat ass about the U.S. but they don't want to strain more their relationship with Europe. U.S. troops are not involved in this war nor are Chinese troops, so this is basically a proxy war.Chinese government's official position on the current Russian invasion has been neutral all along. China is unlikely to change that since providing military equipment to Russia would risk massive US sanctions and asset seizure. I don't expect this to change even after Putin Xi meeting.
But if the Europeans start openly supporting the Taiwan separatists and send weapons to that island, then the Chinese will probably support the Russians in this war, something that will be really bad for the Ukrainians.