Aren't power strips "relocatable power taps" which implies portability/severability? I've heard that power strips can have key holes for mounting because they quickly allow disconnection, whereas a hole with a screw holding it in place makes it more permanent so they can't have those. Rackmount PDUs are listed under a different UL article than power strips (but the rules seem very similar to me). Not sure if those are allowed to be in "racks" that are bolted to the wall, but I don't see much difference between that and a portable rack on wheels that sits in the corner for years.
Most things with cords are severable or fit one of the exceptions in the code allowing cord. A network or alarm box bolted to the wall seems like permanent premises wiring to me. Whenever we had a network cabinet or alarm box installed in a facility, power was run to it in EMT. There frequently was a normal receptacle box inside the networking or alarm Hoffman box so that the switches or alarm power supply inside the cabinet had a place to plug in.
