as far as his meteor comments, just tell him that any chunk of rock half a mile in diameter has the firepower of thousands of megaton nuke bombs going off.
His atmosphere re-entry crap is nonsense. that only applies to objects that WANT to enter the atmosphere without burning up. Earth's atmosphere will destroy most of the stuff that enters it directly or it will "bounce" off objects approaching from certain angles or speeds. That is why the shuttle has to enter earths atmosphere at such a criticically precise angle and speed.
A piece of rock a mile long however, could care less about how it enters atmosphere.. nor will it bounce off because its just too damn massive to bounce off. Think pebble trying to bounce in water.. too big it sinks no matter how hard or how soft you throw it, a small sized pebble will have to hit the water at a certain angle and speed to bounce (depending on its mass).