Robin
If an engine flamed out at relatively low level over an urban area, I can't conceive of a situation where I would remain at low level whilst attempting a relight. Nor would I be attempting a relight whilst in autorotation!
Neither of those scenarios represent 'flying the aircraft' in any way shape or form!
Even on fixed wing, it's like saying one of the
three pilots of the BA 777 that crashed at Heathrow a few years ago should have tried to relight the engines!
I can't be at all sure that the witness statements are consistent with a helicopter simply running out of gas?
I can't comment on the issue of continuous ignition on an EC135 as I don't fly them, but I can only imagine it to be an unlikely configuration?