Oh, hey, I knew someone who helped with research on this while I was at UCSB over a decade ago. From the way they described the goals of their research, it was

Oh, hey, I knew someone who helped with research on this while I was at UCSB over a decade ago. From the way they described the goals of their research, it wasn't so much using WiFi as radar with specially flashed router drivers doing emitting and receiving, that's just a research convenience. The whole point is to passively detect objects using already existing WiFi signals. It's easy enough to figure out where the router is, and if the router is regularly noisy enough, the idea is they would have enough data to work with. The research results from a decade ago was able to pinpoint and uniquely identify humans and weapons. Not hard to guess how that could be useful to the DoD.