>>96387988
It's just this thing. I really wouldn't make too much of it. The actual text in the book it's from doesn't acknowledge it at all. The symbol is seen nowhere else and nobody who's worked at GW has said anything to suggest there was an effort to memoryhole Slaanesh. If there ever was a plan to supplant Slaanesh it seems to have involved very few people and died very early in development, as in well before the game even launched.