Was there a reason why she didn't refer to them as air raid shelters? Maybe not sufficiently dramatic.Panic Rooms? Sky seems to be stretching the mix a bit there. Having had to clamber over a few industrial sites I would think there are more than a few ducts and underground spaces in a port of that size. That doesn't mean they can't be used for nefarious purposes but I'd need more evidence than part of what looks like a ceiling.
Alternatively, constructing voids saves on a lot of unnecessary concrete.