I think he's just excusing his own behavior with that statement. It's no different than his claim that his sexuality was "tampered with" as an excuse for whoreing around and behaving inappropriately with girls*. At what point do people take responsibility for who they are and what they do?
The reality is that there is a random assortment of people in most groups. Yes, there will be some degree of gravitating together in extreme cases but I think overall JWs tend to have the same sort of mix as the general population.
People are who they are. People are not made "good" by leaving any more than they are made "bad" by staying. Certain environments can feed certain personality types - an abusive narcissist for example may find a cosy home as an elder, and abuse their power. If they are subsequently kicked out, did the WTS really make them who they are or is it simply who they always were? I think someone's immediate family environment has a stronger impact on personality than the WTS part of their existence.
Whatever impact the WTS had on people, to imagine it sets the path of your life is really loser-think. You can change. You can reprogram yourself. All it takes is a small amount of introspection and effort if you want to change. If you refuse to accept criticism then yes, you may stay a dick all your life. So he's right in one way.
*that "oh, ha ha ha, I said 'girls', whoopsie!" where he laughs in his video is a pretty sick way to talk for someone claiming to be a CSA advocate.