The essay is great, but I'd like to stop on this for a second:

the conclusion I draw as a science fiction writer is that if interstellar colonization ever happens, it will not follow the pattern of historical colonization drives that are followed by mass emigration and trade between the colonies and the old home soil.

Okay, but we don't need that much of a thought experiment to get there. Gliese 832 c is 16 light years away. That means that even if we figured out every technological issue with calling a colony there via Skype, we would have a message latency of 32 years. Can you fucking imagine negotiating a trade treaty where each round of negotiations takes THIRTY-TWO YEARS? How many Earth governments even remain stably in power for 32 years? Of course transporting the actual trade goods would take even longer. So, you negotiate a treaty over three generations of human beings, and then get the actual goods delivered in, optimistically, a few centuries. We're so good at planning things in advance that climate change will wipe us out in like 50 years, good luck running a trade operation where a freight you ordered will be delivered to your great-great-grandchildren.

With colonisation at best you're gonna get a bunch of disorganised human clusters that will grow culturally and ideologically apart really quick. It's obvious on its face that this wouldn't be a somehow coherent society. Again, how do you plan to organise a government structure where a single memo takes THIRTY-TWO YEARS to be acknowledged? Did anyone in TESCREAL ever grapple with the fact that our globalisation age was brought forth thanks to near-instantenous communications, and that's flat out impossible on an interstellar scale? Like, the speed of light is not something you can hand-wave away, it's a physical barrier to information.