Draw or win? (if black flags)

A knight+king is considered insufficient material to mate, but in this particular position black has no choice but to checkmate himself! (1...a2 2.Nb3#) In a tournament, what would happen if black were to just let his time run out in order to claim a draw by insufficient material? Could white refute that claim by saying that he has a clear win?

Since there is a pawn on the board, white wins if black flags. That is for OTB.

The implementation here is different and would be a draw, if it hasn't changed and I'm remembering correctly.

To claim a win on time, he must demonstrate that a mating position can be set up on the board.

Because of your continuation 1...a2 2.Nb3#, if Black flags, White can claim a win. However if White flags, Black can claim a win, because he can promote the pawn and hence checkmate (e.g. 1...a2 2.Kd3 Kb2 3.Ne2 a1=Q, remember that it does not require perfect play from both sides!).

I can't remember the two players, but in an armageddon game during a Women's World C'ship, black flagged in a KN v KN endgame. The arbiter ruled a draw because neither player can force mate, and the Black player advanced to the next round (having draw odds in the armageddon). The player as White appealed (knowing that the mate didn't need to be forced, only possible), and sucessfully got the result overturned into a White win, putting her into the next round.

Now imagine this: after 1...a2 is played and Black presses his clock, White flags just after. If he didn't make the move at all, then Black wins (because he can promote the pawn and win), but if he flags during or after he plays Nb3#, then the position on the board takes precedence and White wins. But as an arbiter watching, would you be able to determine if Black made the flag claim first, or if White made the move first? And remember that your decision could decide the outcome of the tournament. If there is ambiguity, then the position on the board takes precedence (i.e. White wins). But what if Black shouts out the flag fall, at the same time White picks up his piece? What would you do, knowing that you can't award a draw (it's one or the other)?

Imagine these guys are half a point behind the leaders (who have finished their games), and who you side on wins the tournament (and a nice $150 cheque). And there's no video evidence either, oh and the loser gets nothing.

(Something similar happened during a tournament I played in, both players flagged and they had to agree a draw as per the rules, had the arbiter seen who flagged first (or there been video evidence), the winner would have received £70 instead of just £38 in a share of 1st, the loser of the game getting nothing.)

Arbiter's are like referee's in football; they make the right decision and no-one particularly cares too much (and why would they, it's their job after all!), but they make one wrong decision and everyone is on their back.