Raider179--
The proposed weapon is not really "low-yield", unless you consider a 1 megaton weapon "low-yield" (compared to some of our 20+ megaton weapons I suppose it could be seen that way). A traditional low-yield nuke is something on the order of 1 kiloton, like the Genie A2A rocket our interceptors used to carry.
The risk from fallout from using ANY nuclear weapon, while present, is usually exaggerated. There have been many dozens if not hunders of nuclear detonations right here in the USA, some airbursts, some (all the more recent ones) underground. Is the fallout from THOSE explosions something you worry about on a daily basis? Are all your friends dying of radiation poisoning? Didn't think so. Smoking and alcohol kill more people than fallout ever has. So why worry about the prospect of using one or two bunker-busters in a likely remote region halfway across the globe?
Even then, the guy who's quote you linked only said that you can't trap "all" fallout. Testing in Nevada and other sites as well as computer simulation has proven that while you can't trap it all, you CAN trap signitigant portions of it--further reducing the risk. Is a nuclear bunker buster something I'd want to use with reckless abandon every time the enemy dug a trench? No, not by a long shot. Is it a valuable tool to maintain in the inventory in limitied quantity? Experience has proven yes.
Even more important than having these weapons, though, is making people believe that we will actually USE them if we have to. A weapon is worthless if your opponent knows that you'll never use it against him. This is the REAL issue with nuclear weapons--are they worth building when our enemies are well aware that our chances of actually employing them are at best slim?
J_A_B