Maybe it represents the ability to say "Hey you, stay put, or go that other way; the shooter is right around the corner" from, say, an overwatch point or a drone or something? In that case you wouldn't want the shooter to know. Beats waving your arms like crazy. Just spitballin' here.

It's just one specific use case for this technology that came to mind for the researcher? Mass shootings are a pretty big deal, even if the odds of it happening to anyone is fairly low. Risk mitigation and death prevention seems like a pretty healthy choice for applying this technology, as opposed to saying something like "This could let someone beam targeted ads that only the target can hear!"

"We made this thing, I wonder what we could potentially do with it that would benefit people as much as possible?"

When getting money from the grant system, the grant providers are not neutral parties objectively deciding what the best science to do is, since there is no such thing as an objective, neutral party. The grant authors learn to tell the grant writers what they want to hear.

This is part of why we get such a stream of stories about amazing new breakthroughs in solar, battery capacity, terrorism reduction, etc. that never seem to come to fruition. A lot of times they were never for that purpose anyhow, really; it was just a paragraph tacked on to get the grant.

A sad sign of the times, and it looks like the researchers were in the USA. Perhaps the media people thought this angle with garner their invention more attention.

My thoughts as well. I can almost guarantee this will be used for advertising.