I just blew the photo up and really took a good look at all aspects. The shadow to Kerry's left isn't human. You are correct, it seems to be a piece of equipment.
Kerry is also looking directly at the cameraman's feet (the cameraman seems to be above the subjects in the photo, possibly standing on a stairway.) He is also not squinting at all, unlike everyone else in the picture. Something isn't quite right, but unless I had the negative on a light table, I can't put my finger on it.
But then, we know Kerry is a bloodsucker, so he wouldn't cast a shadow, would he? Or he is one of Peter Pan's Lost Boys, who has lost his shadow?
Now I'm not so sure. It seems the shadow to his left is unbroken, but it falls on a box of shiny ammunition. Those apparent rows of sunlight through a grating seem to be the reflections off rows of .50 cal rounds.
Maybe the photo is legit.