I should also add that the top youtube comment for this video (a transcription of the bird's conversation) is actually the most useful (perhaps only useful) youtube comment I've come across.
Amazon can. That has no information about how the nodes were allocated. They could have hand picked X rack of nodes that were all connected via the same switch, etc. You don't get that guarantee from AWS.
Fair enough, I guess.... they could have done many things.
Although they do not provide an answer, here are some links to additional info - I spent some time searching for additional info on the Top500 setup, but found little:
"Compounding the problem is WVLA engineers can’t get in touch with anyone from the streaming giant to solve the problem."