I see the logic of your progression. However, I think if assad is engaged, he or iranian proxies at that point will use WMD against Israel and damascus will become a slaughterhouse. The horrible thing to consider is whether iran would back down at that point, seems unlikely.
" Iranian proxies at that point will use WMD against Israel"
Fox news this moring is reporting that Iranian troops in Lebanon fired Iranian versions of the
Chinese silkworm missle and that is what hit the Israeli and Egyptian ships.
Israel is under an existential threat. The rest of the world with the exception of some, see this as a regional conflict with Israel being the agressor, since they view the proxies (ie Hezbollah, Hamas, etc) engaged against Israel not as proxies doing the bidding for Iran or other states but borne out of the premise espoused by liberals that these are movements of 'Liberation' against an outside occupying force.
Iran is trying to buy some time. Israel is to them a 'sideshow' that can entertain the rest of the world while they persue their nuclear ambitions.