Except that the dark forest hypothesis completely falls apart when you examine it for more than a few minutes.
SPOILER
Basically, the fundamental problem is that it applies game theory really badly, by treating the value of "survival" as functionally infinite, which is something that - if we actually applied it in reality - would make life unlivable. For example, eating a chocolate bar contains a miniscule risk to your survival. But if you multiply any minute fraction by infinity you get infinity, so the risk outweighs any possible value you could obtain. This becomes true for every decision you can possibly make. At both the individual and societal levels, treating survival as a purpose that outweighs everything else just leads to total paralysis. Any society that operated on those principles would never actually advance to the point of being capable of interacting with the wider universe. Liu even has to treat humanity itself - our only extant example of a space-faring species - as an almost impossible outlier because our own behaviour completely shatters the hypothesis. Even our studies of animal life on earth repeatedly demonstrate that curiosity and altruism are actually traits that evolution selects for, not against. Yeah, it solves Fermi's Paradox, but that's literally the only argument for it. It fails every other test possible. It's a really interesting idea for a scifi setting, but it's not remotely supported by reality.