As reductive as "just send self-replicating robots" is, it's still potentially easier than a self-sustaining human civilization like the article is talking about. Both require building the entire set of infrastructure to build industrial infrastructure and computers. The robot approach requires that every single factory and excavator is automated* - a huge feat. The human approach requires every piece of infrastructure the robot one does, plus the infrastructure to make pressurized domes, oxygen, food, heating, etc, etc, and also requires shipping large numbers of humans through the vacuum of space - also a huge feat. I don't think it's a given that either approach is easier.

* At least, automated enough that it's not bottlenecked by humans operating robot arms at a 30 minute feedback delay.