Though I still don't quite understand what is the original question here. I have not read Diamond's book, so I don't know what he is exactly trying to explain. The phys.org source talks about "Eurasian political and military dominance".
First, the focus on Asia (in addition to Europe) is strange. The renaissance, the industrial revolution, the demographic transition, secularism, constitutional democracy, institutionalized science etc all started in Europe and not in Asia. So apparently Diamond tries to explain the current political dominance of (some parts of) Asia. But then he would need to also take into account the US, not just Europe and Asia. So I don't really understand what we are trying to explain here.
One important point that hardly anybody dares to mention is that people of East Asian and European descent have significantly higher IQs than people from other geographic areas. Personal IQ is highly correlated with measures of life success, like income, highest education degree etc. Moreover, national IQ is substantially correlated with per capita GDP. We also know from twin studies that adults have similar IQ to their biological parents, not their adoptive parents. This suggests IQ causes both personal and national success, and isn't just correlated with it.
So arguably the task should not be to explain some sort of "Eurasian" dominance, since this dominance can likely be explained sufficiently with IQ as a proximate cause. The open question is rather why people of East Asian and European descent have a higher average IQ. Or why modernity began in Western Europe, not Asia, despite East Asians today having higher IQs than Europeans (excluding people of Ashkenazi Jewish descent, which have higher IQs than both gentile Europeans and East Asians).