In retrospect, it's kind of hilarious that the player doesn't just rip off the bangle after that scene - you still do guilt damage in the fights after Nightmare Chirithy.
Gameplay and story segregation at its finest.
Strictly spoken, anyone who doesn't want to "become" a traitor to the light and turn into a Seeker of Darkness should refrain from using any dark medals/cards at all as they're also represent the power of Darkness just like the guilt/sin.
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As for the question if Maleficent traveled to the past or the "Player" to the present it is also possible that neither is correct because in the Realm of Sleep there is no time flow. If this is all a dream/in a dream world present day-Maleficent just entered that dream world, she didn't really time travel.
Dreams have to do with sleep, one of Maleficent's primary attributes so it is feasible that she's good in this stuff.
There's also this part from Ansem SoD in DDD that might become relevant to Chi-characters as well:
Dreams hold our memories. Sleep holds our dreams. And darkness--it holds our sleep.