The issue is the assertion that Iran can't be relied on to not launch nuclear weapons because they somehow are too insane to fear MAD.
That wasn't in evidence from your response to NGTM originally, and I confess I had just been skimming the thread until that point.
While I wouldn't go so far as to claim the Iranians are too insane to fear MAD, NGTM made a very legitimate point earlier - it doesn't have to be too insane to fear MAD, a simple failure to fully comprehend what the other side is thinking can be enough to render MAD useless.
Even during the Cold War, MAD doctrine was always a shaky concept at best (despite what some analysts still say on the subject) because the Soviets and the Americans did not fully understand each others politics - there was always the very real possibility that one side could misinterpret the other's actions and the nukes could start flying due to nothing more than an innocuous mistake in interpretation. Fortunately for all of us alive today, the hotline was established to help resolve these issues following the Cuban missile crisis when cooler heads realized that MAD only works if you understand the position the other guys are taking.
The trouble with Iran today is there is a massive disconnect between the position of their leaders, and the position of the Western world. We really don't understand Iran, and they sure as hell don't understand the rest of us (a fact that's done nothing but get worse since the 80s). The trouble with Iran entering the nuclear game is that the rules, so to speak, are already fairly-well established, but the Iranians are quite likely not to realize that fact. Unlike Pakistan and India, which both had relationships with Western powers that basically said "here are the rules we're all playing by, don't do something outside the rulebook that looks crazy to the rest of us," or North Korea, who got the memo from the Chinese, Iran doesn't have a real nation sponsor. China is a major economic partner for them, but the foreign policy interaction seems to end where the money stops. Russia has little to no influence there, the Middle East in general despises them, and the West is collectively tearing its hair out. For MAD to work, Iran needs to understand the game. Whether or not they will is an entirely open question, which means MAD doctrine as far as the Iranians are concerned is unreliable, and therefore Iran having nukes is a really bad idea.
I didn't get the impression that NGTM was saying that Iran would rush out to nuke Israel, more than Iran cannot be relied upon to understand the rules by which MAD operates and therefore there is a distinct possibility that they could be willing to use nukes or nuclear threat in a way that they might deem limited but the rest of the world would not. Middle Eastern politics are crazy by anyone's standards - the Israelis have also shown a willingness to use nuclear weapons outside of the traditional limits of MAD (it is surprising how few people know how close the Israelis came to using them in the Golan Heights), and it really isn't that far a stretch to see an Iranian willingness too.
So to address Joshua's original post in the thread: no, MAD is not still in effect when it comes to the Middle East. Letting Iran develop nuclear weapons is a really bad idea - not because they would immediately rush out to nuke Israel, but because their actions are not predictable by other nuclear-armed nations.