The researchers at the Pentagon were reportedly looking for nonlethal weapons.
They concluded: “Application of the microwave hearing technology could facilitate a private message transmission. It may be useful to provide a disruptive condition to a person not aware of the technology. Not only might it be disruptive to the sense of hearing, it could be psychologically devastating if one suddenly heard ‘voices within one’s head.’”
Was it likely that Alexis was a target? No. Impossible? Also, apparently, no.