It actually goes beyond Carpenter, Gellar, and Boreanaz. Julie Benz (Darla), Amber Benson (Tara), Emma Caulfield (Anya), Michelle Trachtenberg (Dawn), Eliza Dushku (Faith), Clare Kramer (Glory), Nicholas Brendon (Xander) and James Marsters (Spike) have all issued statements of support for Charisma. If you have this much of the cast coming out against you (imo), your behavior is really scummy and I don't think forgiveness should be given so easily.
Not to say that you feel Joss should be easily forgiven, I'm just piggy-backing my reply off of your post.
It depends on what you mean by no sexual accusation. Yes, no one has come forward and explicitly said: "Joss sexually assaulted me", however Michelle Tratchenberg posted this on Twitter in response to the conversation on Joss' behavior.
“Thank you @sarahmgellar for saying this. I am brave enough now as a 35 year old woman….To repost this. Because. This must. Be known. As a teenager. With his not appropriate behavior….very. Not. Appropriate.” “There was a rule, saying [Whedon] is not allowed in a room alone with Michelle again,”
Trachtenberg wrote, adding she would not be commenting further on the matter.
Yes, his behavior with everyone was inappropriate. However, if it was a matter of generally mistreating people verbally, why would it matter if he was alone with Michelle Tratchenberg? She was only 14 when she was on Buffy, and the fact that this 'rule' was put in place, leads me to believe that there was other stuff going on, or attempted.