On top of that decision, the Operators of the aircraft have to explain why they failed to see a more urgent need to replace the problem studs.
No they don't - the operators' role is not to second guess every decision made by a manufacturer regarding urgency of implementation. Quite apart from anything, they will not have the big picture on in service experience, certification test data and engineering design rationale. Some operators are very large with huge amounts of inhouse expertise (including approved design 'houses' and flight test personnel) others are very small and are constrained by resources.
Regardless of the nature of the operator, the manufacturer conducts the risk assessment and that is the assessment used when planning. To further expand on your logic - what if operators decide to implement ASBs early, how early is early? What if an operators decides to implement a 1 year ASB at the next 50 hour check, but the failure occurs 5 hours before? Should they have implemented it before the next flight? That is not how a commercial operator can function - as I'm sure you know.