>Much as this is nice to believe, having worked in a number of left wing organisations, they are perfectly capable of imploding by them selves. It appears that they attract a certain kind of idiot, who is exceptionally well adapted at persuading other middle-class idiots that black is blue.

This doesn't speak to his point at all. He's not saying all left-wing groups that have been destroyed were destroyed by infiltrators. He's saying that that was the purpose of the infiltration by law enforcement.

The fact that orgs can be destroyed by other factors is true but totally irrelevant.