The end of InReach fixes may be unrelated to his actual accident. Complexity is a regular feature of accidents. The assumption that the end of transmissions is the same event as his accident may be why the search has failed. He may have flown a long way toward Wendover or wherever the conditions looked good without a working tracker.

Nevada is not unusually rugged. The search area images show typical western Basin and Range terrain. If he was in a vertical decent/freefall at the last fix, then the search area would be tiny, and he would have been found right away.