Congrats to Zach for not getting riled here. And can Pythagorean please stop nicking my best lines.
But anyway, I'd like to hear more about how Zach generalises from consciousness to perspective. His model of consciousness so far is sketchy and unconvincing. And I'm am left with no clear impression of what "perspective" is actually a measure of. It could be complexity, or integration, or locality, or a lot of things. So it would be interesting to refine the definition.
As I said earlier, it would also be a help, and more scholarly, to put his own definition in the context of other such efforts.
For instance, there is the semiotic approach based on CS Peirce's metaphysics. There must be 30 or 40 academics currently working on bio-semiosis and pan-semiosis as a way to generalise the notion of meaningful relationships (between observers and what is observed). You also have second-order cybernetics, relational biology, autopoietic systems - a lot of approaches that could be felt to have something to say here.
Reading Zach's paper, I don't think he gets how brains actually interact with the world. That does not necessarily matter as consciousness might be just the "analogy that inspires" here. He could be defining a metaphysical primitive that is useful and only very loosely like subjective awareness. Or he could instead be relying on his sketchy understanding to be exact, the primary motivation of his argument. In which case I would say he is in trouble.