That is in Exodus in the context that God was just asked to reveal Himself to a mortal man "in his glory", rather than as He did earlier in the same chapter of Exodus where He speaks to Moses face-to-face in a different nature that wouldn't kill Moses, i.e not in utter, full-power heavenly glory. If we're in heaven looking at God, then we aren't going to just disintegrate, since we will lack mortal bodies capable of death, but if, in some abnormal case, a mortal were to just witness God in His natural state as he resides outside of our universe, yeah, some crazy stuff would go down involving the mortal's death. So, you don't have to just disintegrate and cease mortal life if you see the face of God, as long as God is in a nature that is compatible with your current comprehension (since we're currently residing in a human form, one might suggest the current, comprehensible nature God could be in for our sake is in the form of Christ).