It wasn't hard to pick him out of that crowd because he had very distinctive wavy hair that you can see in both images.
In the center, do you see the high part and then the wavy hair going back? It's the same as on the right. And of course, he also matches the guy on the left.
For those who have not been keeping up on this what makes this important is that the man on the left has, for a long time been falsely identified as James Bookhout. But, it turns out the Bookhout was very short. They wanted to hide that fact because the Garage Shooter of Lee Harvey Oswald was also very short- shorter than Jack Ruby.
Now, why would they go to the trouble of faking phony images of James Bookhout? It's because he was the Garage Shooter of Lee Harvey Oswald. He really was, and they particularly had to hide his short stature. And this is truly the biggest discovery in JFK assassination research in many decades. I doubt there has ever been anything bigger.