I wasn't a kirk follower so this is all new to me.

Appears he was a standard Israel shill up until a few months ago he started to question things. It means he didn't realize his role as a sociopathic lying propagandist like other Israelis, he actually believed what they were telling them. So when he realized it was all lies, that made him mad.

Someone like that is actually a pretty big risk because you can't just write them off as a crank (as people in this thread are doing even now). The sense of betrayal drives them to a great level of resistance.