Void elves have spoken about how theyre gaining new members. You can even see non void elves studying the void at the void elf zone
So its not that hard to believe that there are elves that became void elves after the recruitment questline.
Outside of that, its completely possible that these customisation options are inclusive of those elves from that scenario. Just like we dont assume a new race of elves popped up when they could use darker skin tones.
Also, as pointed out higher up in this thread, dragonflight has introduced NPCs that use the new options as void elves and not high elves