If Israel ever actually was allowed to cut loose on Syria (such as after an attack by Syria on Dimona) there would be nothing left of Syria. Not a presidential palace, not a base, not stone left upon stone. Assad's regime could not survive, and nothing Iran could do would save it. It's almost worth having them try it, just so Israel can have a moral pass to strike back.
Palestinian man suffers light wounds from rocks thrown by Jewish men in Jerusalem (Haaretz)
from the article: Syrian MP hints Damascus could strike Dimona reactor if attacked