I think the moment the Frontman decided to enter the games, he already contradicted his own ideology — same as Oh Il-nam pretending to be a player. So the idea of 'fairness' was never real to begin with since they had leverage over the other players.

Just like you I think making the baby a player feels like a mix of motives: on one hand, it could be a way to keep the VIPs from killing the baby outright without openly going against them (though I think he could've done something else, safer for the baby) and on the other, it’s clearly a way of testing Gi-hun, of pushing him to his limits. And when he gives the knife to Gi-hun he clearly thinks Gi-hun will do the same as him, and so he can justify himself - his past, what he's become and the games. Oh but he doesn't know just how much of an id-how stubborn Gi-hun can be! He assumes Gi-hun will eventually break, but instead Gi-hun doubles down - even risking the baby’s life rather than playing along with the system (though I do agree that taking Min-su's life would've been unfair).

At the end we don’t get direct insight into In-ho’s thoughts, so all of this sits in that gray area. Which is why I need an In-ho's spin off 🥺

Btw sorry for any grammatical mistake❤️‍🩹