"He's an apostate. Let's go." is code for "Oh, crap! Somebody who knows how to argue with us."
JWs really believe that without them nobody can know anything. If you're an ex-JW, unbelieving JW's family member, or an ex-study, in their minds, you're an apostate. If you know about the Governing Body, you must have learned it from them. People so programmed against independent research can't fathom anyone knowing anything without the Society to spoon-feed it.
JWs believe they are familiar with the Bible, because they are told they are. They are told they have a scriptural education that rivals and exceeds any college degree. Witnesses are convinced the Governing Body is this group of men who - like the apostles - have the Scriptures opened to them by Holy Spirit. In reality, the only reason JWs gain any headway with the people at the doors ever, is because most people know nothing about the Bible and are completely apathetic.
Nearly every JW I've ever seen in action falls apart if their sales pitch gets side-tracked. It's embarrassing how many elders and pioneers I've had to bail out at the doors because they were making us look like idiots. More often than not, someone who says anything other than answers to their leading and fake "personal interest" questions is labelled as "combative".
Some people take offense to someone knocking on their door and telling them about the Bible. When people say they have their own church and the JW continues, it's obvious that the JW discounts their church. At this point, some may understandably get defensive. JWs, not being able to handle any resistance - because the presentation didn't go like it did at the Theocratic Ministry School demonstration - go to pieces, leave, and talk smack about the person in the car. I've heard so many times how "they're rejecting Jehovah, not me." What? I've had excellent return visits with people nobody could ever get anywhere with. JWs refuse to understand this simple concept: Nobody cares about the stupid Watchtower! Show them something useful from the Bible!
I've discovered JWs are very uncomfortable around anyone who actually is familiar with the Bible; especially if they know you're not obsessing over the Watchtower articles. And most elders hate anyone who obviously has a more firm grasp on the Scriptures, especially if they have decided that one is "spiritually weak" because they don't worship the Society the way they're supposed to.