I was on a sub and we were in the yards for overhaul twice. I don’t recall any restrictions of that nature on the yardbirds. Mind you that was more than 30 years ago and I’m sure some things have changed.
I was in Brememton in 76 for a new core in the reactor - crew did fire watches and oversaw every civilian on board. Assigned one-on-one when they came aboard to work.
I heard years later they stopped that practice and civilians were used for all work in the yard and went unsupervised except in the “nuc” sections of the boat. At that time Aft of frame 57.