Lyudmil Tsvetkov wrote:
Concerning the real TCEC game, this is quite similar to FIDE rules concerning the situation when a player has been flagged, but he has just delivered his opponent a mate. In this case, although the flag of the player is already down, thus losing on time, he still wins the game, fully according to FIDE rules, as there is mate on the board, which overrides flagging.
Correct: I cannot claim a draw by 50 move rule if I have just been mated. Mate tumps the 50 move rule. Conversely, you cannot claim a win by mate-in-two if I can claim draw by 50 move rule first.
Very similarly, based on TCEC special draw rule, the game was declared drawn, but, when Cutechess adjudicated the tablebase position, it adjudicated a win, as the position is simply won. An existing win on the board, which is the case in current game, actually an existing mate, certainly overrides the special TCEC draw rule.
This, however, completely misses the point of what happened here.
The game was not declared a draw, and there was no mate on the board. The game was halted in a position that is drawn under the 50 move rule, but adjudicated as a win because of the existence of a mating line that ignores the 50 move rule.
Now, it could be argued that the referee has no business adjudicating a game as drawn under the 50 move rule: it is up to the player to claim the draw in that case. That is a separate discussion. Of course the UCI protocol lacks a way for engines to do this anyway, which is why the referee makes the claim on behalf of the player.