So you torture your man to reveal where it is. What's to say he's going to give you the right information anyway? Say he directs the ground crews to Grand Central so you start the search there. After a couple of hours the device in the Empire State Building wipes out the whole of Manhatten. If he's gone to the trouble of getting such a device into place at all he's not going to roll over and say precisely where it is at first, he's most likely more than willing (and possibly actively desiring) to die for the cause in the process.
How exactly has torture helped you here?