I think I sort of see what might have happened there. They copied the old event announcement from PC/Mobile, which included the part about The Emperor being available in the Vault:
They probably didn’t even read through it, meaning they didn’t notice that the announced loot table and the hidden loot table are out of sync.
Just a somewhat educated guess. I wonder how this is going to get handled, if this is correct players will have wasted a huge amount of keys chasing an absent rabbit the past month. I seem to recall some official statement from not too long ago that the release announcement can safely be trusted.