Plot is saving luffy. Kaido just tried to kill him before asura now doesn't.
Yes, the plot is saving it so many times.
1 - LAW and ZORO save him at the beginning of the attack, in 1001.
2 - Luffy loses to DRAGON KAIDO, even after attacking the left and the right with G4, luffy with ACOA and FS, kaido defeated Luffy in time, and chewed him like gum.
3 - Luffy is sent like a ball by KAIDO, who is playing with him, while he was at the base (the PLOT saving him from KAIDO).
4 - He tries to get on top of KAIDO and is knocked out by a beautiful kaido chlorhephy.
5 - Kaido manages to free PHOMETHEUS, save BM, throw LAW on the wall and return to kill Luffy, ZORO saves him again.