It's an open call for anyone to accuse Al Franken of sexual harassment. If you want to garner some victim status, feel like you're a part of something important (#metoo), or if you just hate Al Franken or his politics, now is the time to do it. Everyone will believe you. Nobody will doubt you. Apply now and gain victim status for free!
Just kidding.
I don't know if Al Franken is innocent, but I see perverse incentives to accuse him. To some, the more women accuse him the guiltier he looks. But I'm very aware of the bandwagon effect. The more women accuse him the less likely it is that he has gotten away with it all these years.
Another reason to accuse him is because he actually did it. He was a celebrity so he thought he could get away with it. I don't think it's clear, unfortunately many others do.