I think (i hope actually) it's a "State" thing just like Martha. (...)
prob her playful state cg
I think that would be preferable and perhaps even probable, certainly, though I struggle to see how this behavior would be compatible with her character and just generally make sense.
For starters, even in her playful state - which was my favorite for Lucile when I played anyway - Lucile still only has very limited understanding of sex and arousal. I don't think we see her willfully try to arouse the player character at any other time, nor do we have any indication she is even aware of what would constitute something being sexy in the first place. To her, sex is just a game about trying to make her brother cum. Showing her ass to the player character would certainly qualify as being "playful," but would conflict with what we see of her otherwise.
Secondly, assuming there is some explanation as to why she knows the player character would react to this behavior, it would require her to know that the player character is even peeking in the first place... that, or she is supposed to be spending her entire time bathing pointing her ass at the door.
For this to make sense would require new writing for the scene, possibly requiring the player character to address Lucile while she is bathing and most likely instruct her specifically on what to do... which I suppose
is a possibility. Which is why I hoped that someone would speak up who had actually had confirmation one way or another from the horse's mouth directly (the metaphorical horse, that is, by which I mean Bones, not the actual horse he's recording sounds from... we've heard enough from that one).
Ah, but what do I know. It's just a porn game, it doesn't have to make sense. Right?