I thought it was flipped too, but after I flipped in horizontally I noticed the longer helmet strap of his M1helmet was on the left side when it's supposed to be on the right side.
Unless this Marine has his helmet on backwards I believe this image is in the correct orientation.
I've also noticed that most often marines of the period either have their helmet straps fastened or hanging loose. They didn't take up the Army 'fashion statement' of securing the helmet strap behind their helmet and the liner strap across the front like this -
There was a rumor in the Army that if there was a nearby concussion and the helmet strap was fastened it would break your neck. In reality a concussion close enough to pull a helmet hard enough to break their neck would kill them by shock to internal organs, and they'd be safer wearing the helmet strapped to protect them from shrapnel.