The claim being made here is what I call the "Existential inference hypothesis": that we are somehow, as individuals, sampled from a large ensemble of consciousness across space and time. There is some difficulty in defining the conscious cross-section that governs this sampling process (could you be born a mouse? Maybe yes, but then you probably couldn't be asking those questions... Could you be born a rock? That makes even less sense; but all that differs among those cases is their atomic configuration). I think the sampling in this case might be a soft measure among linguistically capable entities.

What it does is allow some weak inference about the existential landscape, about everything that exists out there. I believe the author's refutal of 'inference from a single datapoint' is mostly wrong -- I believe indeed we're likely some kind of uniform sample, and single uniform samples don't reveal variance. But, there's not exactly a single variable here. We have a pretty large number of variables: population of the Earth, number of Neurons per individual, and so on. It's still not much though to give an accurate picture of the landscape.

I would indeed be wary of taking any hard conclusions from the data. If you use hard knowledge from biology, physics and computational disciplines, you can probably use our "sample" to refine estimates about life in our own universe.

Overall, the most I would conclude from this hypothesis is the following: "You and I probably (but not certainly) typical among numerical living beings in the entirety of existence.". The practical lesson I would take from that is to be thankful for what you have, and do the most of what you can for the world, because the basic donitions don't get much better than this.