Separately, for once:
What the Giant said was that it takes more effort than usual to adhere to a self-made code, because there is no external authority holding one to that code.
You previously conceded that adventuring is not a particularly Chaotic profession, even if it is a chaotic one. Are you going back to that? Because we can rehash that whole discussion, if you'd like, but I doubt we'll arrive at a different result.
Each of these claims is interpreted through the lens of the person issuing them. The Deva considers the LG afterlife the ideal to strive for. The Deva thinks NG is to some extent an afterlife for people who couldn't hack it as Lawful. Roy thinks the same way.
But that doesn't make it so. The CG Deva will have different opinions on which afterlife is the best and which alignment is the hardest to adhere to.
There is a good case to be made, however, that being Neutral on either axis is objectively easier than being on either end of said axis, because people without strong tendencies end up as Neutral, while people with strong tendencies can be anywhere on the axis.