Your disagreement, from what I understand, seems mostly to stem from the fact that shrimps have less neuron than humans.
Did you check RP's piece on that topic, "Why Neuron Counts Shouldn't Be Used as Proxies for Moral Weight?"
They say this:
"In regards to intelligence, we can question both the extent to which more neurons are correlated with intelligence and whether more intelligence in fact predicts greater moral weight;
Many ways of arguing that more neurons results in more valenced consciousness seem incompatible with our current understanding of how the brain is likely to work; and
There is no straightforward empirical evidence or compelling conceptual arguments indicating that relative differences in neuron counts within or between species reliably predicts welfare relevant functional capacities.
Overall, we suggest that neuron counts should not be used as a sole proxy for moral weight, but cannot be dismissed entirely"
I think this post is missing a huge factor : oil.
The Bush family had massive ties with the oil industry, including election funds, and there were apparently plans to invade Iraq before 9/11 according to former Treasury secretary (without a politically acceptable opportunity to do so, though).
More data in this article and the excellent book 'Oil, power and war', which shows that getting oil has always been a major factor in geopolitics over the last 100 years.
Oil is not like any other resource - without it, the world's economies, food system and armies would crash within a week. Access to energy and resources is likely to be a major factor in political decisions as well.