This is a distinction without a difference. If H bombs D, H has lost

This assumption determines (or at least greatly alters) the debate, and you need to make a better case for it. If H really "loses" by bombing D (meaning H considers this outcome less preferable than proliferation), then H's threat is not credible, and the strategy breaks down, no exotic decision theory necessary. Looks like a crucial difference to me.

That depends on who precommits "first". [...]

This entire paragraph depends on the above assumption. If I grant you that assumption and (artificially) hold constant H's intent to precommit, then we've entered the realm of bluffing, and yes, the game tree gets pathological.

loqi remarked about Everett branches, but imagining the measure of the wave function where the Cold War ended with nuclear conflagration fails to convince me of anything.

My mention of Everett branches was an indirect (and counter-productive) way of accusing you of hindsight bias.

Your talk of "convincing you" is distractingly binary. Do you admit that the severity and number of close calls in the Cold War is relevant to this discussion, and that these are positively correlated with the underlying justification for Wei Dai's strategy? (Not necessarily its feasibility!)

I look around at the world since WWII and fail to see this horror. I look at Wei Dai's strategy and see the horror.

Let's set aside scale and comparisons for a moment, because your position looks suspiciously one-sided. You fail to see the horror of nuclear proliferation? If I may ask, what is your estimate for the probability that a nuclear weapon will be deployed in the next 100 years? Did you even ask yourself this question, or are you just selectively attending to the low-probability horrors of Wei Dai's strategy?

Then also, in what you dismiss as "messy real-world noise"

Emphasis mine. You are compromised. Please take a deep breath (really!) and re-read my comment. I was not dismissing your point in the slightest, I was in fact stating my belief that it exemplified a class of particularly effective counter-arguments in this context.