Given that you can not take a picture of a statue and sell the picture, or even publish it, it's even more strange.
Maybe some parents could try to claim copyright on the derivative work? (Ö_Ö)
There's also a case where a woman sued Getty images (and won) after her photo showed up in an HIV advertisement. http://nypost.com/2013/09/19/woman-sues-getty-after-photo-ap...
In those cases, the photos were a major component of the advertisement, and it was strongly implied the people in the photos were associated with prostitution and HIV. The picture in this article is such a generic looking stock graduation photo it might be hard to prove it's implying anything in particular about the subjects.
And it was taken in a public place, so there's no expectation to privacy.
He could try suing, but it probably wouldn't be worth it. Probably best to laugh it off and be happy he got an article out of it.
If you want to make a story about anything university / student debt related, and want to suggest that this is not only a white-rich people problem, this photo fits the bill.
Maybe that's not required because none of the uses imply the subject is endorsing whatever product/view-point the various articles are promoting?
http://www.clickinmoms.com/blog/street-photography-and-the-l...
http://www.pdnonline.com/features/What-Photographers-N-10515...