ABS is VERY proficient in handling different surfaces. In fact, THAT's where it shines most, compared to human control.
As I said, what could have been a problem was her having a more pavement oriented tire, so having lesser grip on the gravel road, and what could have been another problem is, she might not have braked as hard before turning, though ABS could have helped with that as well.
The lower grip level maybe was too low for her turning speed (and skill) at all, but the change of surface would NOT have been a problem for a modern ABS.
Into the dark side of our nature to look we all need. The energy, the passion there is. Afraid of that people are. Pieces of us it holds busy denying we are.
Riding is flowing through traffic like water through a rocky river bed.