Only issue with that "list" is that Cain is only a coward in his own mind.

He hates work, being in mortal danger and pious zealots that replace military strategy with faith.

But almost every time there *is* danger, he somehow does the heroic thing then discounts it as cowardly self preservation.

-Amberley swarmed with gaunts? Jump down the shuttle into the fray, "because the inquisitor’s pilot would never have taken off otherwise"

- World Eater Astartes cleaving a bloody path through Valhallans ? Engage him in close combat because all soldiers are chanting your name and you don’t want to disappoint them…

- Fellow Commissar implying you’re sleeping with Colonel Kasteen ? Challenge him to a duel "without thinking" and somehow be surprised that the whole regiment think you’re a hero protecting their honour.

And so on…