If you want to play non-Baldurian, all you need to do is not picking [Baldurian] choices ... that sounds quite acceptable for me. O_o
Exactly.
I don't have citations to show but I have seen it mentioned that they do want to give custom characters special background stuff relating to being Baldurian. They certainly talk like being Baldurian is meant to mean something in particular.
I really hope they don't force this Baldurian origin on us. They should keep it the way it is now with dialogue choices, because a proper custom character should have the freedom to be from anywhere.