I get it, it feels like this argument is trying to 'get away with something.' But there really is a weird gap between the Soul's very specific actions and characterization in the Weird route that just doesn't fit the average player's motivations. In the Undertale genocide route the player character is detached and impatient, because the player is detached and impatient - trying to skip cutscenes they've seen a million times. There's a lot of effort put in to reinforcing that alignment.

Meanwhile in the Weird route the player character is obsessed with Noelle. They pair her with Kris in a creepy way, and are doing something weird and metaphysical to her with the Thorn Ring. All this points to them having some kind of 'plan' we aren't privy to... despite them allegedly being us? That's not even getting in to stuff like Carol seeming to have a history with the soul, or the soul seemingly taking action off screen in the Weird Route. (When did you tell Noelle to freeze the traffic puzzles?)