Everything takes time. I think it's easier to train a puppy than an old dog for sure. But, I know we had a dog who also didn't like men, she would bark and shake and attempt to bite and attack men with beards. Eventually, with enough training and love and patience, she started learning to get along with men but it did take almost a year to get her fully adjusted. I'm sorry about your dog, losing a dog is like losing a family member!