If the CEO was some boring old white man and he had done the same thing then yes his head would be called for. You are trying to make this an issue of her gender and her race when it is nothing to do with that.
FUnnily enough one of the reasons that she inspires such dislike is because she played the victim of sexism card and then after a trial she was found to have no case. And actually what came out of the trial was the truth about her self-serving behaviour. The trial documents make it very clear that she was no angel, she was sexist toward other females, she hads an affair whilst married, with a married man, and then blamed that on the other person all the while there were text messages and emails showing she was as much to blame as he was.
Coupled with all of this her partner is currently facing a lawsuit on a case of fraud. Stuff like that pisses people off and with reddit there are a lot of users that care a lot about the site, they care about how it is perceived and they see her as detrimental to the site in part becuase of her behaviour as CEO but also due to her behaviour prior to becoming CEO which has been well reported regardless of her reddit position.
