It's ethically dubious because solar or wind power wasn't an option in the 50s-70s. So you're effectively gating the majority of the world off from nuclear power, enjoyed by developed economies. Which would have developed economies of scale (see: France) with the end result of developed countries having access to cheaper power than developing ones.

And I'm confused. Your reasoning around why more reactors wouldn't have increased nuclear weapon proliferation was contingent on only the US, USSR, Britain, and Germany (and presumably countries like them, to an approximation) having more reactors.

Either you get to say that (a) all countries, or (b) only "responsible" (for lack of a better word) countries should have used more nuclear power.

If (a), then you have increased proliferation risk. If (b), then you're establishing (and presumably militarily enforcing) a two-tier ability to access cheap energy, that favors developed nations.

There are relatively few countries which wanted to develop nuclear weapons over the past ~60 years and were unsuccessful in doing so. I see nothing wrong with banning the export of technology and equipment needed to develop them to those countries (AFAIK: Iran, Iraq & Libya). In fact that is already the case and Israel and US already used/are using military or clandestine means to prevent those countries from developing them. So basically I find it hard to imagine that the situation would be significantly different than it is now.

But lets I assume you're right and 'a' is somehow correct (I don't agree with the premise that increase in global nuclear power generation capacity would somehow automatically result in a higher risk of nuclear weapons actually being used) that would still mean that the western world, Russia, China, India, Pakistan and all other countries in their sphere of influence or aligned to them would have access to cheaper power (which is at least 80-90% of the global population). And I don't consider 'because Iran does not have access to nuclear power then it would be unfair for anyone else to have' to be very good argument.

In fact even if only developed countries had access to nuclear power (which is obviously not fair and not realistic anyway, good luck preventing Russia and China export their reactor to whoever they want) I still think that would be preferably to nobody having it.