Er, yeah, I'd compare the kunai throwing thing to a punch.
However, you're wrong about the feet.
Whenever someone intends to throw a single punch, the hitting hand and the leading foot are on the same side, not opposite.
la_luna, I do understand how it's supposed to work, but until a minute ago I still couldn't get my head around him having the throwing hand and the leading foot on the same side.
Just try it yourself. Stand facing your imaginary opponent and enact the spear throwing. The foot that will go forward will be the one on the same side as your throwing arm. It's a matter of balance.
The awkwardness comes from the sideways initial pose, and him not moving his feet on the ground, only rotating them.
So yeah, the opposed limbs are right.
Now, the rearmost foot should stand on the ball of the foot, not fully flat, and the front foot should be almost perpendicular to the arm if seen from above.
Again, you have to remember he starts from a pose where he is standing sideways to his opponent, not facing him.