This is not a policy of guilty until proven innocent. It's a policy of "advertisers don't want to be associated with rapists." And while there is a good argument for allowing access to YouTube as a public square, there is no such argument for allowing access to YouTube as an advertising platform.
Is that even true? Are there no convicted rapists with monetized youtube channels? Youtube does background checks? Or they merely take action when someone's crime(s) make it into the news? That seems rather arbitrary and short-sighted. Some journalist or cabal of journalists can write a viral article about someone, about something that happened a decade or more ago, and a corporation will unilaterally decide to end the economic aspect of their relationship with the person?
I'd also like to point out that a court determing legal guilt has precisely zero standing in terms of actual guilt. Courts are fallible systems that fail every day and are a terrible metric for determining what actually happened.