Lighting and Shadows
One major sure-tell sign something is fake is by looking at lighting and shadows. The time stamp on this photo is 11:29:14am. This is close to high noon, so the sun should be directly overhead. That said...is the time stamp when the photo was taken, or when it was uploaded? Or is there a time zone discrepancy?
The sun is coming from the left. You can clearly a beam of light on his ankle (the one w/ the brace), crutch, and the entire right side of his body is lit as well. His shadow cast is long and narrow to the left, which coincides with sunlight coming from the right. However, due to the length of the shadow, I would guess the actual local time of this photo to be closer to evening (6:00-7:00pm) when the sun is much lower in the sky or early morning (8:00-9:00am). This is a contradiction of the time stamp, but again, we don't know if that is local time.
Additionally, any RPG or grenade launcher that I've ever seen is going to be at least 3ft long. Where is the shadow from the launcher?
I'm inclined to believe this photo was taken in early morning when the light isn't as strong. There is no shadow cast from any of the light poles in the background, nor any from those large decorative bowls that line the street.
Firing the Weapon
It's already been stated that launchers of this type don't have much "kick". That is true. The back of the weapon is open for gases to escape, so the wielder isn't absorbing the shock like with a traditional firearm. Still...I think most would brace themselves when firing launcher, and not be standing in this casual posture.
Also, his clothing is loose-fitting. However, it appears as though he is holding this weapon with just one hand. His left arm looks as though it is in front of him, as the sleeve does not seem to be bent at the elbow as if his arm is raised. You can clearly see his other crutch next to his left foot, which leads me to believe he is holding onto it in front of his body.
Then there is the odd explosion. The timing on this shot would have to be perfect, which is plausible. However, I'm quite certain that any photographer in this situation would be shooting in rapid fire mode. Why keep this photo? Why not keep the one of a smoke-trailed projectile sailing through the air?
What the heck is this guy shooting at anyway? The effective range of an RPG is 200-300 meters (220-350 yards). Because of the angle of this photo, he is firing directly in front of him at a treeline. Maybe he has a gripe with the local forestry department?