The only reason I'm doubting Zoro is because yes he can slice it, but the wood from that ship isn't your average wood. It's much thicker, and way stronger than normal wood, extremely durable too. That's why Luffy was having so much trouble with it, otherwise he'd have punched through it before Hoshi stopped him.
His slashes may not go as deep as you expect them to, considering how tough that thing was built. And unless you have the string of Mihawk to make a slash go all the way through, there's no point in just having them go partially through.
Basically slicing isn't the ideal form of attack to bring down Noah, from my point of view. It takes larger, blunt attacks to do real damage.
