("put the battery in a box: the same thing might happen again, but at least we'll keep going"), without any extra information as to the root-cause, it wouldn't get passed by me or anyone else
Well that is an interesting point. This either means your Ethics Committee is making an engineering judgment in which case I presume it would have access to suitable acknowledged, independent experts in the relevant fields who would point out where the fix was wrong or it is making a judgement as to competence, honesty and integrity of the - in this case - company that builds the aircraft and the body(ies) that certify it.
If the former, I'm interested to understand what you feel is lacking for the following reasons: (sorry if a bit long-winded)
In the example you are using, the 787 battery, Boeing and the FAA and everyone else has said, publicly, that they do not know the root cause. So the solution has had to be to build, and I presume test, a solution that will protect the airplane in the event of every single cell going into thermal runaway. In addition the solution will prevent a single cell causing a cascade failure of the others. On top of that there is much enhanced monitoring and control of the battery environment.
As an engineer I'm not happy that the root cause was not found, but as an engineer I know that very occasionally that will be the case, especially when the evidence is well and truly fried! So in that situation you do what Boeing have done, assume the 'nuclear' failure could occur and design for it.
If the latter, what possible reason would the two bodies have for knowingly and 'with malice a forethought' allow the thing to keep flying until a known risk of a catastrophic event occurred? Such an event, in today's world could, and most likely would, destroy both organizations.
I'm not being antagonistic, just trying to follow the logic.