Alternatively: The average person is not keenly attuned to politics, and isn't as informed as the average politico. Endorsing or voting for Joe Biden isn't an endorsement of China and Communism and anti-white mentalities any more than voting for Donald Trump is an endorsement of white nationalism. Prescribing the extremes of either side to every single member of that political faction generally isn't going to be very fair or very accurate.
Whatever their reasons were for voting for Joe Biden, I'm reasonably certain that "I want to empower China" was not anywhere in the top 10, and more likely than not wasn't even on their minds in the first place when they were filling in the bubbles on their ballots. If anything, it would just be an unpleasant side-effect.