There are even possible motivations for that action. Life absorbs low-entropy energy (such as visible light from the sun), does useful work with that energy, and dumps higher-entropy energy back into the universe as waste heat. But if the surrounding universe ever got too warm—too filled with thermal refuse—things would stagnate. Luckily we live in an expanding and constantly cooling cosmos. What better long-term investment by some hypothetical life 5 billion years ago than to get the universe to cool even faster? To be sure, it may come to rue its decision: Hundreds of billions of years later the accelerating expansion would dilute matter so quickly that civilizations would run out of fresh sources of energy. Also, an accelerating universe does not cool forever, but eventually approaches a floor in temperature.
I don't think this is correct. Things stagnate when energy is used, the universe expanding shouldn't change this.
I like the main idea though (except for the parts where he goes too far down the rabbit-hole), i.e. that life could take on strange forms and that advanced lifeforms could be hard to spot because they're so unlike anything we'd imagine. Instead of focusing on e.g. finding water or whatever, people should pay more attention to finding anomalies.