Italian uproar over judge's 10-second groping rule

tl;dr: A caretaker groped a student. She described walking up a staircase when she felt her trousers fall down, a hand touching her buttocks and grabbing her underwear. According to the judges, what happened "does not constitute a crime" because it lasted less than 10 seconds.

Thought experiment: If someone hit that guy for less then 10s, wouldn't that be a crime, either? Or has the assault to be sexual for the 10s rule to apply? What if the guy was hit with a huge dildo then, would that render the 10s rule applicable? (Obviously an academic question, not encouraging anyone to hit anyone.)