Sanji my boy!!

Big Mom transcends humanity itself, and just as tojiiii mentioned, it would mean death!

Yeah... But I thought, he promised that he would never hit a woman.. Whatever the reason.

There is a comment right above this one that brings up a good point about that.

The whole cake island arc was frustrating. While it added some depth to sanji, the emphasis on him being kind was weird to me. His kindness towards any and all women tends to back fire on the crew, in the recent arc, Nami as well as Ussop and chopper almost died because he decided to protect enemy women in the middle of a war with two emperors. If he doesn’t want to fight women he should target men. Instead he rushed into the lions den. Indirectly he’s responsible for bringing bigmom to battle with kaido. He hasn’t reflected at all. Zoro is picking up his slack but sanji is still arrogant towards zoro. Even though zoro was pissed back on Zou for taking action alone and putting everyone at strategic disadvantage. Zoro hasn’t said anything to sanji, when if he pointed out how he left brook, Nami and chopper vulnerable when he was in charge of the safety it would put him in his place. Sanji even attacked luffy on whole cake island. I was honestly shocked when zoro didn’t treat him differently when they met again. All of this doesn’t really paint sanji as kind. But as immature person with superficial ideals. He doesn’t act like a leader anymore. He was showing his leadership skills on punk hazard and dresarosa, and part of zou. But it disappeared the following arcs. And it’s frankly ridiculous to call him kind with luffy right there. The emphasis the whole arc how sanji is secretly kind but he was cruel to luffy and luffy forgave him and accepted him even as he was attacked. Luffy has the heart of saint for his loved ones. And now it’s biting him in the butt. Btw why didn’t anyone stand up for law when his crew mates were accused. If luffy was there he would have been pissed. Nami especially understands luffy’s view on loyalty and friendship. Both sanji and her specialize in stealth. And Nami has gone to law for protection in the past when Mingo attacked. Why has the trust and friendship been broken down. I’m afraid there’s going to be a bunch of true betrayals soon.

You said Sanji "rushed into the lions den", but he actually did not actively go to fight a Black Maria and her lackeys, he was tricked by them. They pretended that a women was being harassed, and Sanji, being himself, rushed in. So he did not actively go there to get in trouble, he was tricked into going there.

It was an obvious trick though. One only sanji would fall for because he will rush into any situation if any female asks for help. The point is Nami “a woman” was immediately made vulnerable by this. So he’s not even being a good white knight at this point because he chose to protect strangers instead of his nakama.