lee and gaara are fast but couldn't protect or evade this attack, they would have died
creating bones under his skin, without losing the ability to move. If the bones can withstand a hit from a chakra infused blade, they can easily tank a hit from a normal blade.
It's be a surprise anyway, since Zabuza won't be excepting it and his last dance creates a enormous forest of bones fast enough that Zabuza won't be able to escape out of range.
And Kimimaro is not slow. He is actually very fast, his stat in "Speed" is 4.5. And if that doesn't mean anything to you he was able to easily evade Gaara's sand (until he sent that big ass wave but that was one of those few occasions when the size of the attack matters more than speed of the defender) which is incredibly fast as we all know. And that was without his CS1.