IF they were that close to the high ground, and barrreling towards it relying on a piece of kit (which would have been less accurate than the on board TANS), to give them a DME countdown to the WP.......,
And presumably, at the same time, totally ignoring the conflicting information (to turn left) from the TANS following waypoint change, whether it was done manually or automatically.
I would have thought that such action would have had the other crew members reaching for the fire axe, as Tandemrotor suggests.