Turning leadership of an already radicalized organization is not what he means. New converts to a group who are actually informants will provoke an organization to radicalism.
When I wrote my original comment I did end up removing that as an option because I couldn't think of any instances where I had reason to believe that it had happened. I'm not saying it doesn't, but I don't see any evidence in that article to support that it does.
[0]https://www.npr.org/2011/08/21/139836377/the-surge-in-fbi-in...