If Halo lore serves me right (don't worry, I'm an expert), that is not a MAC shot at all at all. That is in fact a combination of events that took place in Halo 2 and Halo 3. See, that light is actually MC launching himself through space with the Covenant bomb, of course, he went so fast he travelled through time and also tore right through the ship. That explosion is just the bomb travelling at speed and thus detonating downwards. The moments after the blast are reminiscent of the opening scene in Halo 3 when the Chief falls into orbit. Noble 6 is nodding as the marines acknowledge on the intercom that their reading is that of the Chiefs signal. He must be thinking, "We'll be ok, Johnson has him now."