Joe Biden's win will make the us political ecosystem back to normal. In other words, It has negative impact on BTC' value.
The political system will be back to normal that is true but the economic system is going to be even worse, I am sure their money printing policies are going to take a turn for the worse as the government does not know how to solve any crisis except by printing more money, but what will they do when the crisis itself is caused by printing money? Print more money of course.
And the more money is printed the fastest the loss of value of fiat against everything else and the faster the growth of bitcoin will be, so if anything I think he will be even better for the price of bitcoin over the long term.