My reading of the excerpt from teh article is that Franks is not advocating this merely predicting what will happen. I agree as to what should be done to any officer openly advocating this.
Tommy Franks is not that far off from many on this forum as to what would probably happen should a city be taken out by a terrorist nuke.
I do not for one think it would happen unless the most likely target for a nuke were the site ie. Washington DC. If the weapon took out a majority of Congress and the POTUS and VPOTUS much of the SCOTUS along with many thousand mid level government employees we would have a brief paralysis of the US government except for the military. Recognition of the dangers is of course the way to avoid disaster.
On a postive note, remember that all military officers take a solemn oath to defend the Constitution, against all enemies, foreign and domestic.
If some General Clark tries to make himself the big boss, he won't last long. Loyal officers will be looking for the senior surviving official in the line of succession, no matter what WMD attack we suffer.
Of course, if smallpox etc is loose, the President may decide to eforce virtual marial law in selected areas to prevent the spread of the disease. To do less could be national suicide.
If the nation is wiped out, the Consitution won't matter, will it?