I agree it is a storm in a teacup, but surely telling a rape joke in the company of women has never been acceptable.
Supposedly he had a few verbal warnings along the way, so he must have known he was making people uncomfortable - maybe that was his intention - so for him to now plead his innocence is a bit rich.
Also just for info none of the employees would have been his, they will work for the BBC. Many will be quite junior and lowly paid - it is difficult to voice a complaint in those circumstances. It's the standard imbalance of power and probably why most of the complaints are by the celebrities.