All -- what do you believe is an appropriate response of APM (ArduPlane) to a complete air frame failure?

Over Thanksgiving break, I test flew an Experimental Airlines AXON build (in a remote, rural area). The plane was flying fine with default settings, and I flew from FBWA to RTL to Auto. During the Auto mission the main spar (an oak dowel) failed and the wings collapsed at around 300' AGL. The plane, as you might expect, took a nosedive to the ground. If my recollection is correct, I could hear the motor running at full throttle as the plane headed to the ground -- my guess in an attempt to pull itself out of the dive. I didn't have the time (or the reflexes) to switch to manual and cut the throttle myself.

Is there ArduPlane code that could somehow detect such a failure and cut off the throttle?

I certainly don't plan on this happening again -- carbon spar from here on out -- but you never know...

Thanks,

Eric