It means nothing if he gets up with no damage a second later.
That's not how it works, buddy. If we're debating durability, then those hits that made Saturn bleed wouldn't do anything to Kaidou; in short, Kaidou's body is more durable than Saturn's. The question is how both deal with things that can damage their bodies. Kaidou is already winning 1 to 0 here because his body is harder to damage than Saturn's... However, we need more answers to reach a conclusion. When Kaidou is superficially wounded, he deals with it by resisting the attack with his insane endurance + Zoan recovery that makes the wound disappear. Saturn deals with it using regeneration. We have to wait and see if this stuff is infinite or finite, if it depends on his endurance, etc...
I won't be surprised if Saturn becomes the new Marco.