Oda still said Shanks is a good guy tho. Just because he’s likely a WG worker doesn’t mean he isn’t kind hearted
I truly thunk its actually a bit more complicated than black/white evil.
Imo (purely a guess), Shanks' grey stance comes from his dual role as a WG family and Roger's alleged protege. Personally, I think he's using Luffy for something that in the end, sounds altruistic or good, but too extreme for Luffy to agree with.
And this is what makes the best Antagonists. This is why I hope it pans out this way, because even if Shanks has "good" motives, he can be a fully fledged antagonist that ties us back to the beginning of the story.
I really do hope Oda has intended for this twist to happen, it just has so much potential for the overall story.