It's not a contradiction, though it could have been worded better. You're not ever going to be able to tell with certainty that data is not being leaked. As a p

It's not a contradiction, though it could have been worded better. You're not ever going to be able to tell with certainty that data is not being leaked. As a person with some sensitive files, does it matter how sophisticated the attacker was? The end result is the same either way if they get out.