A face is shown... What makes it Muhammad's face? Nothing. The caption under the picture, that says 'depicting Muhammad preaching the Qur'ān in Mecca.' That's not much to go on. It could be a volley ball with eyes and a mouth drawn on it, that's just labeled 'Muhammad.' Yet apparently 180,000 people take its genuine faceness seriously enough to fret about its presence on Wikipedia.
When Muslims object to depictions of Muhammad, what exactly is the content of their desire? Suppose philosophers of language established that a causal theory of reference was correct, and historians somehow established that there was no causal chain of the appropriate sort connecting the prophet Muhammad to the picture in question. So it turns out that the face does not, as a matter of fact, depict Muhammad. Would that make the screaming masses happy? Do they really care about something so arcane as the reference facts? Or is it rather the appearance of obedience and acquiescence that they miss (and never mind that nobody's entirely sure just what it is they're acquiescing to)?