Yes, but also, what if he was disappointed? What if this was the “of course this would happen” smile?
Cause so far, Gi-hun is not like the rest. Gi-hun went back to stop the games, he’s “good at heart”. He was going against the Front Man since the beginning, he told him that he was going to show him that the world doesn’t always go the way he wants it to.
Lee Byung-hun said that maybe In-ho is secretly rooting for him. Because maybe deep down he wants to believe that he got it all wrong. Just like Il-nam did, when moments before he died he lost to game, he was proven wrong.
In that very moment, when Gi-hun was planning to sacrifice a few innocent people for the greater good, he was going against his morals. He showed In-ho that maybe he’s not that different after all. I like to believe that this was an “of course you would” kind of smile, that In-ho realised that the man he thought so different and so special, the man that intrigued him, was indeed just like the rest. That he ended up being corrupted as well.
Which makes the scene where Gi-hun gave In-ho his ammo even more intense. Because for once more, he was proven wrong. And their game was still up.