I've seen this before, and here's my problem with his thinking: He assumes events happen organically. To wit, a football is placed on the 20 yard line. By itself, the chances that the ball will cross the goal line are small (wind, etc.) But the chances go way up if there's a team trying to score the TD. He neglects the factor of another actor working towards a specific goal.
Not to fearmonger, but when terrorists are actively working towards a goal, that goal will more than likely happen if we take a laissez-faire approach. Now, does he have a point about creating more haystacks? Of course, but what's the alternative? I dunno. Alot of the current DHS mining isn't only unconstitutional, but isn't terribly effective. Humint is the answer, but we just don't have the horses.