I agree that some of his techniques are lightspeed but Kizaru himself does not move at the speed of light at all times. Marco tagged him from a distance.
Light isn't as op a power as pple have illusioned themselves to believe, light in its natural state travels very fast but never hurts us so the fact that Kizaru can create forms of light that can hurt pple is enough, asking him to move his pinky and KO WB is dreaming.