Bonking is when you've hit the wall by depleting your body's glycogen stored in the muscles and liver. Sprinting uses a different energy system - the Phosphagen System which doesn't metabolise glycogen.
Energy for Phoshagen System runs out after a 5-10 seconds (assuming a fresh effort, which is not the case here). Any kind of prolonged sprint (or sprint after an intense effort) uses glicolysis to generate ATP.