Kirk is speaking, but Khan's not listening - not by the way he lunges at Kirk before the words are even fully out of the captain's mouth. Every movement is calculated, feral intensity - distinctly at odds with the Augment's usual cool disdain. At this moment, Khan is just as much the man he was on Qo'noS as Kirk is.

The bulkhead provides a nice, convenient surface for Khan to try and slam Kirk into, throwing his shoulder into the other man's stomach. Pin Kirk down, knock him out - and perhaps break a few bones for the sheer audacity - and this fight would be over.