Might be just that they needed more time to find someone who knew enough about gyrocopters to ask the right questions.
Absolutely could be. Mind you I thought I read that the AAIB sent two chaps up yesterday morning - so you'd hope they might know a bit. Personally, I am extremely cynical about the motives of Warwickshire Police here; but it will all come out in the wash and at least we can rely on the AAIB to be relatively unbiased.
And I believe that there is still some value in switching off the engine regardless of rotor momentum: at least the propulsion propeller will become harmless almost instantly and you will be able to talk to the intruder more easily.
According to the nth hand eye witness account above they were going away from refuelling, when you would not expect the rotor to be at speed either, but I suppose that even in the early stage of pre-rotation it is going to hit hard.
It wouldn't do any harm, that is for sure. Will be interesting to see in the AAIB report which blade was hit. There was suggestion earlier on here that the rotor blade had some damage, and then later some suggestion that perhaps the rear prop was hit.
Head injuries have been suggested too - so perhaps it was a blade sailing of the main rotor; only time will tell.
(I shall ignore the previous 2 posts, and hope SP deletes them when he has a minute!).