Pits could be made at many locations. Restricted data is the biggest issue. Manuals could be printed overnight and sent where they were needed.

Also in your war scenario the environment would take a back seat.

Also when Rocky flats was decommissioned it was part of a network. Every time a facility is allowed to operate its alternatives are considered. Which means the plans already exist to make multiple other facilities operational.

Also, the pits from the decommissioned, or upgraded bombs are kept. They could be tested and reused in the, to maintain a functional if not perfect arsenal in the mean time.

Also were making less pits on purpose. Idk wtf that article is. Theres an intentional reduction in arsenal and not a whole lot of good defense reasons to amp production. More inoperational bombs at any given time, more likely that a mistake would effect a bigger percent of the arsenal, more like to cause international uproar. What the heck was that article?