Every game is important in such a close race, but he is obviously going to start him now when he has three forwards fit. Home to Empoli is a lower risk game but then this shit happens, it's annoying and changes the game.
Easy to forget but last game he started Milik scored a hat trick. This sort of thing can happen especially when a player doesn't start that often and is trying to make an impression. It's not like Milik has history of it or isn't very experienced, he had a brain fart and it's massive because every mistake counts now.