> Except when we do.
Yes, sometimes. Dark Forest seems predicated on the idea that it is mathematically impossible to ever not be committing genocide because it is the one and only correct answer. Yet here we are existing in a world where genocide is not the goal of every living being.
> As the orthogonality thesis states, intelligence is orthogonal to values. You could imagine smart bears whose values and ways of thinking could be completely alien to us
Irrelevant to their ability to reason. They will undoubtedly value something, else they will not have motivation to take up arms in the first place. Sure, it is possible that they value our extinction as their highest priority, but that seems incredibly unlikely because it would mean that their own survival is less important. If they at least value their own survival higher than our demise, then there is basis for reason.
> I'd argue, because of the first axiom: inability to establish trust due to communication delays.
What does that have to do with trust? Communication delays are equivalent to distance, and being far away from potential dangers has a way of making them less threatening, not more. At interstellar distances you can afford to be patient.
The biggest problem with the Dark Forest concept is that it is predicated on this insane notion that the most important thing in the entire universe to anyone is the continuation of self -- and where mentioned before that self is defined to encompass exactly your own species and no more or less --, which is directly contradicted by both the long history of human and animal behavior and by the fact that everything dies including the universe. In other words, if continuation of self is your highest priority, and you're forward thinking enough to see other species lightyears away as a potential threat, then you're also forward thinking enough to see quite plainly that you have a 100% chance of failure in the long run.