The focus on ratio seems to me to transparently be an effort to preserve the status-ordering that humans confidently believe in rather than ceding status to elephants and other large animals.

Yes, a lot can be explained by status-seeking. But here? Um, I think it's more due to the lack of elephant theoretical physicists.

You clearly don't need a huge computer to run a sauropod brain.

And you don't need to obey the constraints of biological natural selection to run a computer.

Protein computers work differently than silicon ones. Just because you can (theoretically) build a more efficient one, doesn't mean that actually-existing biological brains must have mass-independent efficiency.