It's on the page, dude.
No one is calling Sanji a fragile little thing because is daddy didn't love him. His family beat him up on a daily basis and his father told him "You are not my son I don't give two shits about you", anyone would be traumatized by that.
I don't think anyone is contesting that Sanji was traumatized as a kid, like a lot of characters in the series were. Usopp is a liar because his mother died and he couldn't deal with that, that's a trauma.
A trauma is not the end of the line just a bump in the road, it may fuck up your suspension though.
A while ago you asked me if I was reading the same series, I could ask you the same now.
One Piece spends half of it's time saying "your family doesn't have to be those with whom you share you dna but those with whom you share love".
Zeff is not Sanji's father figure, he's his father. And he taught his son "You can be an asshole, to me or other people, when I kick you you can kick back, I don't care. But if you hurt a lady it will hurt me"
It's not about Zeff commiting suicide literaly, it's about being the total opposite of Judge.
Judge: you cause me pain so you can even hurt yourself and die and I don't care; Zeff: I care so much about you that the only way you'll hurt me is if you break my golden rules.
We saw Sanji being rejected and losing a family because he "failed" Judge. The last thing he wants is to do something that would cost him Zeff's love and care.
So Sanji was selfish and failed his mission until a crewmate came to the rescue. And Sanji knows and admitted that.
Even though he told Kalifa he would beat her up if he had to he failed to do that, because he was brought up with the ideal/principle to never hit a woman.
He wanted to be able to fight Kalifa and safe Robin and protect his crewmates/family but doing that would cost himhis other family and he just couldn't do it.
A character you like did something you really disagree with becuase of reasons the story has already explained.
It's ok for you not to like that scene, it's ok for you to like the character a little less, it's ok for you to think that the course of thinking/action he took is so fucking dumb but that's the way the character is.
That's a nice interpretation, too bad that's all it is. The manga hasn't made this entirely clear. So far we know Zeff told him women should not be hit and that he considers himself as his parent. Hopefully we'll get more background on this, but so far you're just interpreting it in your own way.