Hey, it is apparent that your reading differs from ours.
Investigators are those that will determine the possible or probable causes. There is no certainty that they will discover the certain cause.
The search organization's only link with the investigators is to deliver evidential material to them. Assumptions are purely there to create a viable search plan. Those assumptions may be modified in time.
Now politicians are different again. They are generalists, and while experts at saying one thing and meaning something else, the are not technicians. They may not appreciate or reflect the nuances in the experts report.
For those that are aware, the report is a model or clarity and caution.