Looks real to me. A lot of airlines stage their boarders, letting those with seats at the back of the plain board first, then the middle and then the front.
The story explains that it was taken during the boarding process and another Freeper said the guy eventually was seated in the TWO seats on the row behind where is waiting during the photo.
This guy is just nasty nasty overweight and should have bought two tickets instead of scumming off everyone elses fares.
Nothing looks “photoshopped” in anyway about this phot IMHO.
OK...but no one authenticates it, the people around him aren’t staring (and you KNOW that they would be) and the leg is a solid shadow...in opinion, it’s a fake...and I promise this is true...I have flown just under a million miles DOMESTICALLY with AA...this wouldn’t happen.