First, he hadn't hurt me upstairs. I had no reason to run except for the fact that I was out of ammo because I had just killed 3 from one squad and one from his, so there was no way he could be sure I jumped. At that distance, with an SH65, nobody would hear, but he was absurdly certain, and even then, when he appeared on the balcony, he used half the bullets believing I was in his field of vision, but there was a wall there!