I feel sorry for the pilot, but how could he not see that there was something going on next to the runway? He didn’t see the lawn mower until he was already on the ground? Why not? Nothing looked unusual from the air?
Did he approach from behind her? If so, that was a stupid decision.
I’m sure he feels just awful.
For the same reason that occasionally, an auto traveling 70+ mph on the highway hits a ‘pedestrian’ or deer. An A36 is a 6-seat complex retract, and final approach is around 70 mph.