another kick play

[DJ_NV]

The question that needs to be asked is: When did the foul occur?
One line of thinking is that it (the illegal kick) occurred while the ball was in player possession and therefore did not meet the requirements of anything listed in 10-3-1.
Now after reading your last post, I'm inclined to rethink the situation back toward a loose-ball play because an illegal kick is treated as a fumble. And by definition, even though B illegally kicked the ball, what we have here is a fumble by A because per 2-18, it was "a loss of player possession other than by handing, passing, or legal kick.Therefore, you're right, this is technically a fumble by A behind the NZ before a COP and so meets the requirements of 10-3-1-c. This is reinforced by 2-23-9 that states that an illegal kick is treated as a fumble.
Penalize from the BS which is the PS.