This is a very Important and possible scenario:
There is a possible chance that Mojtaba is in fact dead, and that the regime deliberately selected a dead man as SL.
Why would they do that? In the hopes that israel goes looking for a ghost while ignoring the real decision makers. A distraction.
His "injury" also excuses the regime from bringing him out in public. Of course he may well be alive, but never underestimate these insane mullahs and their desperation.