I need to correct what I said. I went back to the source and, somehow it was "lost in translation" before. This is what Maya Plisetskaia is saying in that interview:
In "Swan Lake", Odile used to be just the daughter of a wicked magician and not a swan at all. So it was the part of a female demon. A woman as a demon, like her father Rothbart, who may even have cast a spell on her so that she looks like Odette and can trick the prince. It's all a great plot. So it's the role of a female demon. But in the West -I don't know who thought this up but it goes back a long way- it was thought that Odile was a black swan. And we took this over. Odile was staged like this and I played it very differently. If she's not a demon but a black swan then she moves differently and she dances like a swan, only she looks different. People think she's evil, so she's a negative character.
As we can see now, Maya is not talking about white or black but about woman or swan. I bolded the words where the confusion must have come from. So the switch I was talking about was not from white to black but from a female character to a swan.
I'm sorry I brought the incorrect information, that's why I need to correct it now, but at the same time I'm glad I'm bringing a new interesting point.