Because even if Pudding was manipulated and abused she was still a villain who was happily involved in assassination plot of someone she knows wouldn't harm her. She may have changed her mind last minute because Sanji complimented her but up till then she was pretending to be nice while being nasty and vicious when no one was looking. Even she was falling in love with him she couldn't completely turn off her nasty and abusive side. She may be changing to be a better person but she clearly needs time to be better.
While I generally avoid stories with Pudding altogether I'm not going to tell people she can't be a villain because she is a villain. Almost everyone in One Piece on some level is a villain. Some just more than others. If a character isn't a villain already in One Piece most will be eventually. I'm not gonna pretend Zosan isn't a villain ship and I'm not gonna pretend Pudding isn't a villain either.
"....who was happily involved in the assassination plot..."
It's obvious that Pudding ISN'T happy to be there. That she's just as much an unwilling victim as Sanji in this entire scheme. That's part of why she's so mean to Sanji as first! She can't take her frustrations out on her mother so she chooses Sanji as her punching bag. It's not because she's an inherently nasty & evil person.
She's just ✨️projecting✨️!!
She resents the fact her mother is making her seduce a man she believes is a shallow POS just like everyone else she's ever met. In part because that is the story Big Mom has fed her & since her entire life has comprised of people finding her hideous, why wouldn't she believe her mother when she's told Sanji will be just like everyone else?
She literally tells her friends she doesn't like how much work it will take to return her very carefully curated life (which she built up in order to be SAFE from abuse btw) to how it was before Sanji came along to disrupt it.
Just because Pudding isn't a perfect victim like Sanji, doesn't negate that she's also just a pawn in her parent's political agenda. Oda very consciously parallels her & Sanji throughout the entire arc lmao. The irony of their relationship is that they BOTH want nothing to do with each other at first & then surprisingly gain feelings during the midst of all the bullshit.
Trying to insinuate that Pudding is at all HAPPY with her life in any way, shape, or form is about one of the stupidest takes this fandom has because THIS is literally our very first look at her in the entire series:
"She couldn't completely turn off her nasty and abusive side"
Oda makes it extremely clear that Pudding's "evil" personal is literally just a defense mechanism she's had to use in order to stop her own abuse from continuing.
This isn't actually true to her nature and she's only struggling with feeling safe enough to be her real self. Something that is actually very common with people who sustained long term abuse and try to rectify + correct their own unhealthy coping habits. This isn't an actual reflection on her as a person.
Something Oda, once again, makes extremely clear through Sanji's own dialogue!
So yeah, I'm going to call out people who continue to write Pudding as inherently evil or nasty. A Pudding who never falls in love with Sanji and is actually 100% exactly like her "evil" persona is not even getting into a relationship with Sanji in the first place! She is not staying to abuse him, SA him, and especially not cheat on him. She would simply leave as soon as she could and never look back! She would actually never realistically fit into the evil ex trope and people who try to stick her in it have obvious underlying misogynistic issues with her character that need to be worked out.
It's gross. It's weird. It's only excused because degrading Pudding's character is almost always used in service of propping up another Sanji ship, typically yaoi ones, and usually Zosan in particular.
Finally, it doesn't matter how much this fandom falls for the anti Pudding propoganda or how determined they are to completey ignore her true characterizartion because I will always be right there to shove the source material in your faces. That way you'll always know your are objectively wrong about her. 😊💖
Oda gives way too much fucking credit to his fans sometimes because I can almost guarantee if we had known Pudding was "evil" BEFORE the rest of the characters & the rest of the story stayed the same with her eventually falling in love & getting her backstory she'd be a fucking fan favorite! Because fandoms LOVE a redemption arc. Oda took a creative swing and it was beautiful & amazing & so entertaining, but too many of y'all were simply not mature enough to handle it. Too many of y'all cannot understand or appreciate the irony and multilayered subversion with her character & it's a damn fucking shame.