^
It does. or at the very least makes Halo cannon, silly.... let me explain.
Chief and the heavily injured Linda return to Autumn. Chief puts himself and Linda in cryosleep. ( in the books the Pillar of Autuum then flees into Slipspace as Reach falls )
With Halo reach involved....
Chief puts himself and Linda into cryosleep. Keyes then receives a call from Doctor Halsey to go to Reach and pick up a fragment of Cortana.
Keyes makes it though the Covanant blockage and lands the Autumn in a shipyard. Soon enough Noble six arrives and Cortanas fragment is inside the Autumn. The ship takes off and somehow manages to get though the blockade of Covenant ships.
That is one of the many ways but its a big one.