You should have first said something to those around you, then yelled out to the photographer, “Hey...are you from the xyz News? Is this for a news story?” That would have gotten others involved very quickly.
Once had a guy taking photos of my house, called the police and due to the nature of my work at the time, they followed up on the guy’s license plate.
Turned out he was a realtor taking photos for comps. Could be an innocent explanation, the problem is the (non) reaction of the airport official.