Signal-jacking and gps spoofing is the only cost-efficient and scalable way to bring these things down. The word gun really mangles the reality of counter-drone solutions
Advanced research technology from the 90s, no doubt. Abandoned due to legal issues. Perhaps it's time to bring it back.
I don't think it's very viable around aiports.
Unless the operator is going out of his way to use a critical frequency as carrier it should actually be relatively trivial to signal-jack the drones, assuming you do it in a narrow beam (thus that you know its position) rather than blanketing an area.
> gps spoofing
That's the part that seems unadvisable near an airport.