Which is to say, the concept works just fine with D&D as Gygax reportedly always DMed it, but doesn't work at all with nine-sector alignment as written.
Well, keep in mind that the OP pretty explicitly says, "Don't just reject the premise."
My analysis above was, more or less, an effort to show that either (1) the premises
really are just contradictory, like asking for a triangle with four sides or a married bachelor, or (2) if they
aren't contradictory, the price you pay for avoiding the contradiction is simply too high for most folks. Because the whole point of the thread was specifically to do this with Good/Evil, and not take any of the easy ways out.
The interesting question left, I think, is whether muscular neutrality works in 1977's five-alignment D&D. If human survival/flourishing requires a balance between the cosmic forces of Law and Chaos, but the only cosmic force that is neither Lawful nor Chaotic is Neutrality, there's room for a case that the promotion of the good might require preventing the ultimate victory of (one of) the cosmic forces of Good.
The main issue here is that it flips the "muscular Neutral" problem on its head. Instead of them being irrational flip-floppers doing bizarre things, you start having both Good and Evil doing that. Because now Chaotic Good forces have to team up with the "muscular" Neutrals and Chaotic
Evil forces in order to prevent a Horrendous Space Kablooie.
Meaning the people who love freedom and self-actualization have to team up with literal demons, serial killers, and drug lords in order to take down....folks who have done nothing wrong other than being Lawful Good, because the Universe plays pernicious games of balance and will flip the table if anyone gets too uppity. The fundamental weirdness of
somebody suddenly flipping sides just because one entirely-blameless group has gotten just a little bit too powerful is still there, we've just changed who it links with.