If true, probably for a number of complex reasons. I couldn't tell you who's who in that photo, for one thing. If anyone were to come out and say they were in that photo years ago, how would they prove it? Especially after the US Marine Corps told the world who was in that photo? Who, even with the truth on their side, would dare challenge them without ironclad proof? And it might not be enough to prove that they were in the photo. They'd be expected to out the guy who wasn't in it, too, and that would be another burden of proof.
But imagine if, too, after the end of 50 years, they could look back and say it was more than enough honor for one man to be a US Marine, who fought on Iwo Jima (and had proof enough of that), didn't let his buddies down, made it home to live a good life in the greatest nation on earth, and didn't have to make a big deal about it afterwards.
My thoughts about it which you touched on is those Marines and one sailor were representative of all those who fought and sacrificed much, some sacrificed all for our country.
In my view it should be left at that and that this investigation is not needed.