Getting a group picture is never easy. It requires everyone to take the matter seriously, and all look in the same direction at the same time. It sounds simple on paper, but anyone who's ever tried to take one knows that nine times of ten, someone moves, pulls a silly face, or generally spoils the mood. The guy in the green t-shirt has had enough of this practice. The face of the boy in the white cap is unsettling him, and he wants something done about it.
Fridman didn't think that giving white cap boy a new face was the right way to go about things, so instead, he decided to correct the mood of the photo by giving the boys either side of him the same face instead. Now, the mood is consistent right along the line - until we get to the guy in the green. Suddenly, it's him who's ruining the tone of the shot.