As others said, it's likely Tsuji came to effectively the same conclusion as Rei, Rei just wasn't seeing that side of things since he's used to playing a more aggressive style.
Come on dude. He cannot be winning games by luck at this point in the story. It's all been downhill since he met and played against Souya and I'm really not liking where the story's going :/ It's like he's going to either stagnate or retire completely because he's satisfied with his life now and that's just stupid as hell.
He is lucky that his opponent resigned right before he did. Most likely he didn't have any more moves to make, and a few good moves from MC would made him lose for certain.
Kiriyama was so caught up in his "I'm losing" mindset that he didn't see that.