Pace
My point was not that making a safety case was invalid, it is that the EU generally get upset by arguing on a national basis.
The IMCr is being seen as the UK solving a problem that does not exist elsewhere in Europe (whether that is true or not, that is how it is seen) and the other members don't take kindly to the UK trying to railroad them into taking a different line, based on national interests.
All other countries engage in a lot of behind the scenes negotiations and horse-trading. I don't think the UK reps at political level, where it counts, do that well enough.