Snoopy was not quite as bad as your new pup but she was frightened of Carl and men in general. I think the FAVORITE treat is a really good idea. Also slow movements, encouraging the dog to come to him, talking gently. At the dog park, when one of the men would lift his arm up to throw a ball, Snoopy would run away and start barking frantically at them. If a new man still moves too rapidly toward him he barks. But if the man puts out his hand, lets him sniff him, he will gradually approach and let the man pet him. I think patience is the key word here.