here it is, more directly: https://twitter.com/gravislizard/status/879758601186758656
about halfway through the thread he basically describes "what if we pay one or two people with powerful servers to run a really big instance" but the other thing he says a bunch of times is that mastodon's interface is bad, which is pretty much true. It is nowhere near as quick and easy to use as twitter.
I know Chelsea Manning is on here somewhere, I think she's probably actually active, but gosh if I have no idea how to find her and follow her.
Calvin keeps saying "upstream" and if that refers to the flagship node(s) as far as I can tell, they aren't really upstream, they just happen to be big and being peered with that node doesn't exactly do anything for us for content on smaller nodes. (And, xychelsea is not on that specific node anyway.)