It would be a limit that is exceeded. Nukes should only be allowed to be used in 2 situations IMO:
1) A response to WMD.
2) An existential threat. Like Hezbollah has overrun Israel's positions in the north and they are coming to exterminate everyone.
Why? Because it unnecessarily kills a whole bunch of innocent people. Israeli's goals can be accomplished by killing far less. And, it raises world tension remarkably. Now Russia can think about getting away with a nuke, Iran might try some form of WMD attack on Israel.
And by "allowed" I mean allowed by the democracies of the world without the most severe of economic sanctions.
My current guideline is the
section on "international humanitarian law" in the Wikipedia article on Collateral Damage.
Its three essential points are:
1. If you place your military forces within a civiilian population, you're committing a war crime. Your enemy is not committing a war crime when they attack you there.
2. There must be a valid military target of an attack. Spamming bombs into a civilian population in the hope of "getting" a few insurgents is a war crime.
3. The risk to civilians from the attack must be proportional to the military value of the attack if it succeeds. Overkill is not a war crime. Overkill of civilians when attacking a low-value target is a war crime. (Corollary: If the only weapon available to a commander in his moment of need is an overkill weapon, it is not a war crime to use that weapon to accomplish a valid military objective.)
That said, I don't think nuking Gaza is the right solution. Certainly not the kind of mass destruction of the entire strip that TGZ seems to have in mind. But even targeted use of precision high explosives against specific hardened Hamas positions would cause a lot of collateral damage.
What I find interesting is that TGZ stipulates that it would be right for Israel to end Hamas, but offers no opinions on how Israel might go about achieving that righteous goal, in a way that satisfies TGZ's sense of morality.
Obviously he thinks nuking the Strip is right out. Presumably he thinks that Israel shouldn't just lie there and take it, even though he thinks it's their fault Hamas exists and has grievances in the first place.
So what's TGZ's idea for how Israel should do the right thing and end Hamas, in a way that maximizes harm to Hamas while minimizing the risk of harm to the Israelis carrying out the work, and minimizes the risk of harm to innocent bystanders?