jesus christ this is so classic TTW in a nutshell, impossible for people to back down on their belief, even when presented with clear visual evidence. "b..b..but his coach said." Don't care, look at the pictures.
Let's do it slowly, with simple brief sentences.
This is an eastern grip. Fed's index knuckle is right on the middle of bevel 3. That's a textbook eastern forehand.
Here is Stefanos again. To help you along, I dotted his index knuckle in red. Hopefully you can see where it's positioned, but by this point I am not too hopeful, so I will spell it out: It's smack on the middle of bevel 4. What does this tell us? Stefanos clearly does not hit with the same grip as Fed or Delpo, his palm is rotated visibly further down to the point that his index knuckle is on a different bevel.
NOT THE SAME GRIP
the idea that you cannot conceivably have an open racquet face with a semi-western is also pretty wild