It occurs to me that technically speaking Malpheas is going to escape in the end after all.
Not the largest bit of him unless he means he's literally what remains of Ligier, stuck to the only imperishable thing available to Malfeas as a desperate makeshift lifeboat, instead of some minor demon of his but still.
From a primordial perspective since Usum still exists Molly could arguably be taken as an extension of Malfeas' existence, and the formation of Molly's soul-world as proof of his final victory over the exalted host.
Then all that's needed is to clean up the ages of neglect so we can plug the divine Xbox back in and it'll be like the primordial war never happened.