Unless the women are, uhm... very slow or the bathrooms are lit with 5k halogens I suspect the images he captured were more architectural then anatomical/biological or anthropological(?). It looks like another case of the police overstepping their bounds and picking on the innocent photographer.
Since they used the word "footage" think they mean a pinhole motion camera, of the type commonly hidden in clocks, wall hangings and such. I think these are usually marketed to catch cheating partners, make sure nannies are treating the kids properly, and spy on employees to make sure they're not stealing.
Even if it was a pinhole still camera - isn't more about the intention than the result? I think this is more about the process of taking the picture without the permission or awareness of the subjects .. or is it? Then again, how would that be different to street photography, other than these women being in an environment where they expect privacy ...? it is very much food for thought.
I guess if there is a law that says you must not act in this way for voyueristic purposes, then it will all come down to the guys intentions.
Some dumbasses tried to stick up a police station for money the other day. Being stupid does not excuse one from breaking the law, it just reduces his or her chance of success. In fact, having spent most of my adult life around the police, I believe that as many crimes are solved by stupid actions by criminals and/or the police getting a lucky break than by TV-type detective work.