Claw Sharpen is ideal for things that have bad stats, bad movepools, or no other boosting moves. Nidoking doesn't possess those qualitiesYeah, Claw Sharpen is an ideal move for certain things and it's by no means terrible.
I think Nidoking boils down to either a stallbreaker (very powerful) that gets outsped by faster, stronger things, or a Scarf variant that loses a lot of power. Sort of a hard choice to make, in my opinion.