I would have thought after the Solheim cup incident players would know better.
A girl did that against me this season, I let it go but after the match told her that some may pull her on it.
I think the girls face said it all, spotted an opportunity for the win and took it.
Ultimately Moon fault, but to answer question no, not in the spirit of the game and poor sportsmanship. View may differ if she had run it past the hole but that putt is made every time.
The girl did nothing wrong. She tried to give the putt but that is against the rules, you can't give it after.
Probably one of the only times that having a rules official walking with the group was bad, had she not been there the incident could have been overlooked.