Why do intermeshing helicopters use asymmetric airfoils? I am referring to the Kaman K-max and the Kaman Huskie here. They both use NACA 23012, which is an asymmetric airfoil. Any reason as to why this is? Is there a different mechanic in play when intermeshing rotors are considered? Does Reynold's number change due to factors that don't affect normal helicopters?

Edit - I can see how my question can become very broad. My question would be answered if somebody could explain what factors come into play in intermeshing rotors that affect the choice of airfoil.
Helicopters in general use asymmetric aerofoils because they are not required to fly inverted or produce negative lift. Intermeshing helicopters are no different in this regard.

The exception would be aerobatic model helicopters, which use symmetrical aerofoils because they are designed for similar performance either way up.