Wait, the player was subbed on during the run of play? I thought he was just returning to the field from an injury? If it's a case of a sub coming during the run of play, I'm not sure I've ever seen that in international play.
Normally, ScorpionRunner you are right, even when an injured (and off the field/pitch), you see it from a dead ball situation and you just play down a man until such point.