The watermarks are also on the other images that they've licenced from Getty, and the unwatermarked image is credited to the photographer.
I'm not sure that there would be all that much value in creating new images for the story though, if a cheaper stock image can communicate the same thing.
In a local newspaper, I once saw an article about some gang members being arrested for making and distributing fake coins that were worth some $5 in my country, and there was a huge photo of a coin with this caption: "A legit coin"