And who is going to take his place? There's no Dem who could pull enough moderates at this point in the race to win. Biden never wanted to run to begin with, but was pressed into it because was the only possible candidate with enough appeal to beat trump (except Bernie, but Dem leadership messed that one up).
The only reason his debate performance matters is because all the never Trumpers who spend too much time doom scrolling are forcing it into the news cycle.
If Biden bows out now, Trump wins.
I assume your concern is with security, so then whats the difference between running the install script from the internet and downloading a binary from the internet and running it?