Agree on almost all your points. However, my argument is that 2 engines are not automatically safer. Safety does not only depend on the amount of engines but whether we like it or not on budget, training and for twins lots of experienced crew.
Knowing CHC worldwide, their core business(unless it is a SAR contract) is offshore support. Having done that, it is not just a matter of cancelling a personnel transfer for a rescue or delaying a rig for a rescue and I do not believe they are capable to allocate a 61 for rescue.
Does the military train with the rescue services? I would think there is more involved than just the NSRI.
I must state that I do not believe a 206 to be a good rescue machine because of it's limitations being stretched during rescue. However, you will have to look hard to beat a B3 Squirrel with a twin. That is where the problem comes in with just condemming singles.