You are smoking something good if you are seriously suggesting that anything Nami or Robin has ever done is worse than what Sanji constantly does. He groped Nami’s breasts and threatened to strip her down and take pictures. He has turned invisible in order to spy on unsuspecting women taking baths. He walked up to a random woman and sniffed her. Hell, despite it not being canon, Film Z was overseen by Oda and included a scene in which he was sexually interested in watching a child develop into a woman. Again, not canon, but it was obviously overseen and approved by Oda, which shows how far the creator thinks he can go. Suggesting that Nami and Robin are in any way as bad as he is, is peak nonsense.
It’s not drinking “SJW Koolaid,” it’s being a decent human being.
In response to him feeling the body he was in she punched him and seriously knocked him out due to his reduced durability.
Touching the body you are in with that body's hands is different to normal groping. Even if he didn't intentionally touch them with his hands, he'd feel them through his clothes as they moved, there is no way around it.
It's a strange situation and I can guarantee 80%+ of straight men, if transported into the body of a woman, let alone one with massive breasts would do some sort of feeling or touching, and I think most women would be curious and check their new equipment also, so let's not be hypocritical. They probably wouldn't do it as openly and brazenly as Sanji is doing it for the gags, but they would do it. Usopp and Luffy only found this funny so I guess they are scumbag enablers who need to be cancelled.
Smoker stripped Tashigi and showed off her body to everyone around him.
Sniffing is a little creepy, sure, but not a crime, again it is the brazen way it is done for gags rather than the act itself, smelling the perfume of a woman is normal to a certain extent, and women do this with men's cologne also, more subtle in the real world but not a crime.
Peeping on bathing is a common fantasy in Japan, to the point it is an anime trope,
https://japantoday.com/category/nat...into-girls’-hot-spring-bath-during-class-trip. LOTS of characters engage in this behaviour if given the chance : Vivi's dad/ Igaram/ Usopp/ Luffy/ Chopper/ Matsuge in Alabasta. Oda's mindset from the SBS when asked about Shiryu is that any red blooded male would try to use the power in this way, so don't bring this up as a Sanji only flaw, 80% of the male characters in One Piece would abuse this power if they could, One Piece after all thrives on it's comedy, don't try to cancel or kill it with real world logic from manga exaggerations.
None of Sanji's perversion is as morally bad as Nami's domestic abuse by any stretch of the imagination (if we extended it to real world logic like you want to do with Sanji's perversion).
In terms of the film 1) minutae like that probably aren't under Oda's view, he does character designs and some loose ideas and lets them run with it, any more involvement is pure hype to get more fans to watch it. 2) she was mentally an adult 3) It was less sexual and more romanticised, seeing the moment she becomes the Nami he already loves, it was even framed with a wedding dress. 4) it was an exaggerated gag.