Islam is completely different: to depict the Prophet representationally is deeply sacrilegious and offensive to Muslims. I am not saying I take the side of censoring when there is a historical or academic use (like I assume this painting is), but there is no need to be purposely offensive, is there? Aniq hardly went Charlie Hebdo about it; he asked politely and suggested an alternative. It didn’t warrant a sarcastic riposte.
In other words, there is more than one way to “recognize” a historical figure, and depicting someone can be done in other ways besides just showing a picture of their face.