Here's the problem with this:
- All King has done is direct other to kill Momo. I'm not sure when it was decided that he was going to do it himself. He was entirely free to do so, but then decided to block the hole in the sky from any intruders until Marco started fighting him.
- Yamato makes Sanji redundant in protecting Momo. Sanji has no idea who Yamato is, so thats the only reason why he's contemplating a rescue. If they do meet, its to do the "sexy woman" gag and have Sanji tell Yamato that the scabbards are in danger. Pretty much the size of what should happen here.
- They don't have beef from a previous clash. Thats made up. King dropped and left him after that clash. Its not like he continued to fight him or wanted to after that moment. Its also not like Sanji was angry he got hit, he saved Momo already. And thats just it, he ALREADY saved Momo and passed him off to Shinobu. Why would Oda draw Sanji taking Momo AGAIN lol?