Seems to me that if a shipyard was getting relocated or abandoned, the stuff would have been moved along with the ships.
I prefer to think it was a plot of some sort that got disrupted. The shipyard was already abandoned and some yahoos were using it to store up materials for nefarious deeds. They got caught but never spilled the beans about where they’d laid up all their ill gotten gear.
A shipyard would not be abandoned without reason. Perhaps they had an economic meltdown when their Dems in their Congress refuse to allow opening of new copper mines. Their pharaoh was too young to have situational awareness and soon it was too late for an overriding Pharaonic Order.