@uniaka:
I imagine the Whole point of SHs qutting the crew and join again is to let go of the past and go with the present and future, the crew. Sanji's past is what got him here in almost no escape situation, like Zeff and germa. And SHs save him from his past so he can focus on the future and go after his dreams. Not awful hypocrite, but the Zeffxist rules stand in the way of his dreams, and friends if they ever needs rescue from girls.
And it's not just sanji, but it was with nami, robin, usopp, and I imagine everyone will get it. Even jimbei if at some point fishman Island gets in trouble. even zoro has to let go of his pride and beg his rival to train him.
The difference between Sanji and the rest (Nami, Robin, Ussop, and Zoro) is that the positive person in Sanji's life laid down that rule. Nami is money-hungry due to a negative influence (Arlong), Robin was distant due to a negative influence (WG and how people betrayed her), and then Zoro's pride is a self-made thing (he had it in spades even before Kuina died).
If Sanji's 'respect' for women came from having only females be nice to him and he grew with a warped vision (women are motherly, women are kind, women this, women that) I would totally agree that there would be a good chance for Sanji to change his ways. But the fact remains that Zeff laid down those rules and in Sanji's eyes Zeff is his saviour, father, and he cannot disobey him. He doesn't want to bring shame to Zeff's teaching or be the source of disappointment.
I would gladly eat my own words if down the line Sanji is able to divorce from his unhealthy obsession with idolising Zeff and his teachings but that would make out Sanji into a big hypocrite and I don't know if I like that alternative better… However for this to happen then idol and saviour 2.0 (Luffy) has to have a problem with Sanji's ways because as seen in Ennies Lobby: almost being killed by a woman or said woman being an accomplice in the almost-execution of another crew mate (female too) is little incentive for Sanji to suddenly change his ways.
Clash of idol ideals to create conflict within Sanji. But going back to chapter "Liar" (good timing that the anime is almost there) we are given the impression that Luffy 100% accepts who Sanji is. Flaws and all. And it just wouldn't be Luffy if he minds the flaws of his crew mates.