To explain: the Outside View is a powerful tool, but one sometime should reject it based on even more powerful factors from the Inside View, where one can be sure that one is in a new (or at least, different) reference class from the one being used in the Outside View. Of course, one may want to reject it based just on one like one's views...

This sometimes leads to a back-and-forth series of arguments over burdens of proof dubbed 'reference class tennis' where the two sides argue over what is the correct reference class which will either support or undermine a particular claim (is AGI in the reference class of "additional incremental innovation", which would undermine claims of significant danger/reward, or entire "regime changes", which would support the same claims? This is the game of reference class tennis which Eliezer and Hanson are arguing their way through in the link and related links).

Kaas is humorously parodying a side using an Outside View involving the Neo-Sumerian Empire, replying to the other side making the commonsense position - yours too ('what lessons?') - that the quasi-literate agricultural Neo-Sumerian Empire from 3000 years ago is not in any reference class that matters to us, and implying that the speaker is writing the other side off as rationalizing and excuse-seeking. The parody works because we agree that in this case, the Outside View is not applicable or its weak evidence is overwhelmed by Inside View evidence about how different the Neo-Sumerian Empire is from any contemporary societies or organizations or processes, and this reminds us that often Outside View arguments simply may not work (eg. arguments from evolutionary psychology, which draw from time periods and societies even more distant from and less like our own than the Neo-Sumerian Empire).

And now that I've explained it entirely, I can no longer find it funny. I hope you're happy.