Here is a interesting Paragraph in the manual

"Once the ECU detects a loss or invalid RC signal for over 0.5 second, it sets engine power to idle, and if after another 1.5 seconds a valid signal is still not received the engine is shut down."

So I suppose one could set the rx throttle failsafe to a parameter well out of the normal running signal if your radio permits (125% throttle down for example ) and experiment with this feature to see the outcome.

I am happy with mine shutting down straight away in the event of signal loss and rx failsafe as it could still be running by the time it meets the ground with a 2 second delay before shutdown, which to me is not a preferred outcome..

edit: I see this has already been discussed, wished I had noticed, not sure what else there is to add.