I would expect that a change made to an aviation fuel that has an adverse effect on any aircraft, is part of CAsA's responsibility.
By changing the lead content in the fuel it seems to have had an impact on the safety of helicopters used for mustering operations - I say CAsA has a responsibility to restore the safety.
I further say that to make a statement, to put it down as soon as possible is not a very good safety response from the regulator. But rather than direct the fuel back to the previous lead content until further testing is carried out, CAsA would simply suspend all mustering operations (possibly fixed wing also) until replacement engines that can operate with the new fuel are designed, tested and fitted with silly restrictions such as happened with Jabiru engines.