Technically, a tool does not need to understand its purpose to be useful and effective. Locke would never have knowingly destroyed the hatches, but unwittingly he has been manipulated to do just that. Locke played the game and then decided to enter the numbers even though he did not know what exactly would happen when he did. That is risky. He did not even ask his other companions what they thought about the prompts the computer was offering. If he had, they might have told him the place was wired with C4 and not to mess with anything. That is just the kind of guy you want at the computer to set off a booby trap.