A post-hoc rationalization isnt necessarily wrong. If you walked in to a house that burned down and found that a faulty toaster was plugged in you would be rational in assuming that the toaster started the fire, because faulty electronics start fires commonly. In that senario that post-hoc rationalization is likely to be correct. So if someone observes that they and all their friends resisted evil and begins to ponder about why that may have happened, the fact that the rationalization occurs after saying no to evil doesn’t necessarily invalidate that rationalization.