I don't really think it should be a question of belief. To me it really doesn't matter what I personally believe happened. It's that the hypothetical choice I have before me of whether I have the enough certainty in Bob's wrongdoing to punish him. I'm an HR rep, my job isn't to access truth in the universe.

The stats argument is clever but I don't think I could support it. I don't think a person should be punished because of the actions of people he doesn't know completely outside of his control. In another universe where false accusations are more common it would mean you make a different decision despite all the facts of the case remaining constant.

Why don't you think reasonable doubt a good standard in this case? I recognize that I try to err on the side of not punishing people but if I can seriously say that Bob really might not have done it then I don't think I could hand down judgement.