The reason for the software discussion was the possibility that we were looking at jpgs and there may have been a processing error, either in camera or in other software. It isn't unreasonable to rule out all possibilities as to why a $1000+ lens isn't performing to snuff.
As for returning for exchange, That's all well and good. He May get lucky and the next one will be better. However, these are not made to order lenses. They are wholesaled in lots. Meaning, the chances of him getting a lens from another lot may not be all that great and the entire lot may have issues. A repair or realignment may be the best bet in this case.
Now, if you're tired of reading the thread, the simple solution is to use your browser's back button to leave and read something else.