Actually, Dearborn didn't want to confirm what we were all thinking. He has come up with a strategy for the best use of nuclear weapons. A strategy that might be quite useful should astronomers see an extinction event asteroid on our doorstep.
Dearborn has outlined two general guidelines:
1) If the asteroid is small, and we have a few decades to deal with the threat, it would be best to detonate a nuke next to the asteroid to nudge it slightly off course.
2) If the asteroid is big, and we only have a few weeks' notice, detonate a nuke on the asteroid, hopefully ripping it to shreds.
The main advantage of a nuclear explosion is that a massive amount of energy is released rapidly, making the technique highly efficient; a nuke can be used to nudge, knock, slow down, speed up or destroy the space rock.
Personally, while I agree with Dearborn that nukes are our most powerful defense against asteroids, there are many other factors to consider.
Firstly, what if the resulting explosion rips the asteroid to shreds, but big chunks of asteroid then rain down on Earth, blanket bombing entire continents? Choosing whether to get hit by one big asteroid or a shower of smaller (but still rather big) asteroid chunks isn't a choice I'd want to make.