It sounds like a setup to me. The girl probably had a gang of dudes waiting outside to kick his ass, which could not happen inside the mall. For one, cameras. But also, security guards are not going to allow some sort of ruckus like that to go down inside a mall.
The actual police? Probably wouldn't care much about "harassment." It would have to be an actual assault or rape for them to do anything. And if they wanted your nephew, they'd just show up where he lives, haul him in, and question him on their own turf. It isn't like they don't know where to find him. The police here know EVERYTHING THAT YOU DO. Everything, seriously. There are cameras all over the place in this country and if the police can't find you it is because they don't care enough to look.
Sounds like the girl chose the wrong story with which to lure the nephew out into the open for his ass kicking.