Ooh, I can explain this perfectly. Some, ESTPs tend to fall into different psychological issues such as Narcissm, Psychopathy, ADHD, and Bipolar. NPD, which I am has a problem with detachMent(not getting close to others), so is bipolar disorder due to the fact I am also one we tend to withdraw Emotionally and not want to be around others when depressed. As for psychopathy and ADHD, we are a type that needs to keep ourselves occupied mentally or we get board.
Speaking for myself, I tend to be a all(either playing the field or committed)or nothing type of guy. People tend to think ESTPs are liars based off our description, this is untrue we just don't like talking about our feelings or problems. Did he specifically tell you what his type was or did you assume based of generalizations, which is very common for most people?