No, I don't think he is. I though Killer App implied a game that would push people to buy a console in large amounts. Titanfall gave the X1 a boost but it was pretty short lived, so I wouldn't say it's a killer app. I mean, by that logic inFamous is also a killer app, but I don't view it as such either.
But usually when a game sells a lot, it attracts more people and if a game is exclusive it could help push them towards the system. So it is a system seller.