I attended the match live earlier today. I just stayed there from 6pm to 10:30pm so I don't have time to rewatch the match from WTT's YouTube channel or go to ESPN 3 since the match was held at table 1 in the Maverick arena.
So this is purely by memory. I recall Darko was leading in the third set and was going to win 3:0. But right in the middle of the set, the umpire faulted Darko for one of his serves (automatically rewarding the point to Shinozuka). Darko was clearly rattled. In the audience, a couple people yelled out for Darko to challenge that call with TTR. But Darko did not. That call literally changed the momentum because Darko ended up losing that game in deuce 11:13. If that service fault was not called, Darko basically had a very high chance to close the match 3:0.
Fourth set was tight. The deuce in that set just went back and forth, and back and forth. Finally it was 16:17 in favor of Shinozuka. Darko served and got faulted (again for his toss not being verticle). Automatically he lost 16:18. Everyone who is involved in sports (like table tennis, NBA or others) would find that situation very strange. Usually in the end of the game situation, referees would tend to swallow the whistle and let the players play out. It is upsetting for fans when an NBA game ends because a foul was called in the last 2.5 seconds and the free throw ends up determing the outcome. Or fans probably are not too happy if a foul was called late in the game and a team won the soccer/football game via a penalty kick. In this case, the umpire literally turned the tide toward Shinozuka, again and both sets won by Shinozuka were clearly by the service fault calls. At that point, a couple audiences also yelled out for Darko to use TTR challenge. Darko just stayed silent.
Fifth set, Darko started pulling away. At 6:9, with Darko leading, Shinozuka served. Darko immediately called for a TTR review and informed the umpire that he was challenging due to Shinozuka hiding the ball with his head. Mind you, the umpire did not call anything but Darko requested a TTR review (I did not know that players can do that; I thought the umpire has to make a service fault call and the server could ask for a challenge; in this case, the RECEIVER initiated the challenge. Earlier in the match, Shinozuka was warned for hiding the ball with his head already once. In this situation, Darko took the initiative and won the challenge which means Darko is now up 6:10 with a free point awarded. Darko then won the match point and finished the match.
In the post game interview, I don't think Darko was upset to win it in this manner. He even mentioned that he was faulted three points. And to me, if he had the right to challenge Shinozuka's serve (and Shinozuka's serve was already warned once by the umpire for hiding it with his head), he deserved the win. Darko was a good sportsman. He even mentioned that he could have won 3:0 (I know exactly what he meant). I felt that his tone might have been a bit sarcastic too; I believe in the post-match interview, even he mentioned he could have won 3:0. He also talked about how some players routinely hide the serve. I don't hear him even implying that he felt bad winning this way.