My point is that people can and have disagreed about what we would think to be even the most fundamental assumptions of the alignment wheel. Including with the guy who invented it.
Im not using Gygax as my moral compass, and I see literally no reason why anyone would (or should). Even if his own
personal moral compass of 'genocide and slaughtering children because Nits make Lice is LG' was the basis for the alignments in 1E (and that's debatable), it's in no way applicable to any other edition (particularly since the alignments themslves were redefined afterwards).
For example in 3E, I challenge anyone to read the Book of Exalted deeds and come away with a Gygaxian 'kill them all' interpretation of 'Good'.
I've provided my definition of 'Evil' and it's one that is used (and has been used) for millennia to regulate human conduct via criminalizing or prohibiting behaviors and is the basis for much of any nations criminal code.
Evil is broadly speaking 'harming others'. Murder, rape, slavery, genocide, torture.
Good is broadly speaking 'helping others, at personal cost'. Charity, compassion, empathy, mercy, altruism.
Captain America, Spiderman and Superman dont kill people, engage in slavery or genocide or rape people, because they're Good people. Thanos, Frank Castle, the Joker do do those things because they're Evil people.
It's a broad definition, that is commonly understood by most. I mean, good luck publicly arguing any of those things I mentioned are 'morally good' things, because (by consensus) they're not.
If Gygax wants to argue otherwise, he wasnt the first, and wont be the last, but I certainly disagree with him, as would most people.