I just love Sanji's indignant expression when he hears Krieg mocking Zeff's current life as a cook. And also Zeff's explosive yelling to the cooks blaming Sanji. Those two scenes imply how much they genuinely care for each other beneath their seemingly hostile relationship.

Additionally, if Sanji had managed to get the food for Krieg’s men, the blame would have fallen solidly on his shoulders. Not just the cooks blaming him for causing calamity, but him blaming himself. It would have been another burden of guilt on his shoulders and so Zeff took it off his shoulders hoping that would be enough so the cooks wouldn’t go railing against Sanji.

I've never thought deeply about the underlying intention of Zeff giving out food to Krieg's men but come to think of it, that's a pretty good point. I guess Zeff's action was to protect Sanji rather than to manifest his own conviction. Though whether Zeff would have refused to help Krieg's fleet had it not been for Sanji I can't say for sure. Zeff did state to Sanji that he's going to feed anyone who comes to the Baratie no matter how villainous they may be. That's the one premise which serves like the very cornerstone of the Baratie, after all. Anyway I think Sanji thought Zeff would understand him putting conviction over preserving the restaurant, after all they've gone through on that god-forsaken island.

In the chapters you covered in this post, Zeff stole most of the show. Like you said, he let the cooks have their own ways, all the while not losing control of the situation and thereby asserting quiet but immense presence. I guess the reason why Sanji is accustomed to the ways of pirates is not just because he grew up fending them off, but also because Zeff treated his cooks very much like a true pirate captain would; Letting them be themselves so long as they don't hurt crew unity. He really is a great character(and foster father)! No wonder Sanji is such a huge badass :)