Many physicists have pointed out several flaws in the dark forest theory, which makes for a great read but doesn’t really carry over to the real universe 1:1.

Did you intend to say dark forest hypothesis?

suspecting that star explosions are caused by nefarious super-intelligences is just Greek mythology with more steps.

In what way? This is discussing, as far as anyone knows, an entirely natural phenomenon.

I think a fragile world hypothesis is more interesting and scary.

Instead of a superintelligence killing any emerging intelligence, superintelligence is so smart that it can perturb spacetime in ways that easily kill itself.

Kind of like the idea that LLMs will give anyone with a garage the ability to create killer viruses (wild claim), a superintelligence might trivially create black holes that engulf it. If the intelligence is distributed across many agents (or nations), someone will try something stupid that kills the entire population.

It'd be even scarier if they could accidentally collapse the supposed vacuum state. Universal annihilation at the speed of light just because you got too smart.

Fragile world / fragile universe meets "too smart for your own good".