Well, he's being charged with having child pornography on his computer. Whether or not he was the one who put it there and used it is debatable.
As someone else noted, it seems statistically unlikely that so many people who the government brings national security cases against are pedophiles.
One of the following must be true: a surprising number of all government workers in intelligence are pedophiles, pedophilia and propensity to leak government secrets are highly correlated, or the government is planting evidence.
I'm not going to discount the mental health correlation possibility, because being crazy enough to work for the government and then ineptly leak classified materials... doesn't bode well for an individual's baseline mental stability.