Ethics

As Bobacus sees it, the specific case is more about intervention than justified action. But what comes to mind is the story of the GoodSamaritan, particularly its context as an example of what is meant by loving your neighbour as yourself. Looking up 'excusable' on webster, brought back (excerpt):

synonyms EXCUSE, CONDONE, PARDON, FORGIVE mean to exact neither punishment nor redress. EXCUSE may refer to specific acts especially in social or conventional situations or the person responsible for these <excuse an interruption> <excused them for interrupting>. Often the term implies extenuating circumstances <injustice excuses strong responses>. CONDONE implies that one overlooks without censure behavior (as dishonesty or violence) that involves a serious breach of a moral, ethical, or legal code, and the term may refer to the behavior or to the agent responsible for it <a society that condones alcohol but not narcotics>. PARDON implies that one remits a penalty due for an admitted or established offense <pardon a criminal>. FORGIVE implies that one gives up all claim to requital and to resentment or vengeful feelings <could not forgive their rudeness>.

Bobacus thinks 'extenuating circumstances' is the key phrase in this case. 'Justified' means it is right to perform the action (or not). 'Excusable' means it is wrong, but that right-minded people seeing the circumstances may choose to neither seek punishment nor redress, and be justified in that position.