Well, it depends on what you want I suppose but I see no reason why he HAS to be taught to allow strange men to get in his face. It's kind of like the guy that told his doctor "my arm hurts when I bend it like this" and the doctor saying "then don't bend it that way!". The only way any man would be scared or shocked that a 4 year old male GSD that he barely knew got uppity with him when he got into his face does not know canine behavior and therefore was probably petting him over his head/neck/shoulders which translates to dominant posturing and could have even been petting him over his eyes which is not comfortable or soothing to a dog in any way shape or form.
Your dog sounds very vell adjusted, and will deal with the things he's not crazy about as long as they are not in his face. I would be happy with that and manage the rest. You can let people pet him if you want, but make sure they know how to pet a dog and supervise them.
Your dog sounds very vell adjusted, and will deal with the things he's not crazy about as long as they are not in his face. I would be happy with that and manage the rest. You can let people pet him if you want, but make sure they know how to pet a dog and supervise them.