When Steve Hassan talks about the cult persona, he means the facade people put on to fit into the cult. As we know, JWs do bad things all the time, they are no better than anyone else.
For example, a person may be a typical JW, clean cut, says he love field service, and watches only PG movies. In reality that guy might really like hard rock and secretly would love to get a tattoo and ride a Harley. He might even do some of those things in secret, but his true personality is not acceptable in the cult.