I don't know much about how a router would be configured in this particular use case, but I'm really straining to think of how this could be useful for espionage.
Most encryption takes place at the transport and application layers, and since this equipment is presumably carrying primarily mobile traffic, that seems an unlikely medium to be exhanging worthwhile secrets. Stealing crypto keys doesn't make any sense unless you've intercepted and stored all the traffic going between those routers, and if you can do that without being noticed, sending one dude to get 16 of them one-after-the-other is a pretty dramatic dip in sophistication. And - as has already been mentioned - unless the nonvolatile storage isn't encrypted, you'd have to get the keys in situ, which would negate the point of stealing the entire physical thing.
Sounds like a whackjob trying to halt the spread of coronavirus by taking out 5G or something.