It's not a matter of whether he'd pull the dagger back or not, it's a matter of once the foot hit it, he wouldn't have time. The pommel would be hitting his gut before he would be able to pull it away, reflex or not. 

And it's all the other leg motions that would require perfect reactions and multitasking. Sliding, leaning, extending, and contracting perfectly to mitigate the damage caused. Crouching by itself wouldn't be enough to avoid the kick, and without all the other movements he made to adjust his weight (movements and calculations that he wouldn't have time to do) it would still hit with considerable force.