Why not just phrase it in terms of utility? "Justification" can mean too many different things.

Seeing a black swan diminishes (and for certain applications, destroys) the usefulness of the belief that all swans are white. This seems a lot simpler.

Putting it in terms of beliefs paying rent in anticipated experiences, the belief "all swans are white" told me to anticipate that if I knew there was a black animal perched on my shoulder it could not be a swan. Now that belief isn't as reliable of a guidepost. If black swans are really rare I could probably get by with it for most applications and still use it to win at life most of the time, but in some cases it will steer me wrong - that is, cause me to lose.

So can't this all be better phrased in more established LW terms?