The honor zoro meentioned was about their 1v1 fight, sanji was interfering and zoro knocked him out, affirming to kuma that he's a man of his words, i can't link pictures but if you backtracked to the start of the fight you'll know that zoro forbid anyone from interfering because it's a matter of honor, he was fighting for the rest of the crew.
Kuma looked at sanji's body knocked out on the ground, and he realized zoro's resolve to keep it 1v1, and so after zoro surrendered his weapons kuma agreed on zoro's proposal, as his honor is also put on line.
Kuma decided to kill zoro with the pain of luffy, he healed luffy and forced zoro to take the pain, it's a brutal punishment, and for what reason?if not only because luffy is more famous than zoro.
For luffy kuma was just gonna kill him, but he walked zoro through hell. It wasn't about "life for life", it was luffy or all of the SHs, kuma realised that zoro was not only fighting for luffy but for the rest of the crew, even zoro said it "it's the only way to save the rest of my crew".
Zoro cartied the entire crew on his back at that time, even if kuma didn't mean to kill him, he still gave up on killing luffy because of zoro.