As someone with all my primary social interaction outside family being online, I'd definitely see that punishment as closer to grounding than solitary confinement! Moreover, I can see why your mom is taking measures to ensure he can't contact your sister anymore, so I'm wondering how much is intended as 'punishment' and how much is 'preventative measure'. I also think this wasn't her fault, though. Dudes like that can get pretty good at convincing kids it's their idea, that they're old enough, that they're soooo mature. She was making unwise decisions, but he was presenting those decisions to her. Like... idk. I'd definitely focus follow-up more on 'why what he did was bad' over 'why you made terrible decisions and deserved this', although that's not the only two options.
Like, okay. Spoiler: Personal stuff, CSA warning I got taken advantage of when I was so young I don't even know how old I was. 5, maybe? A male relative of a friend of my mother's was entertaining me while my mom and her friend talked, I think he might have been a teenage son of the friend? I just remember he was a lot bigger than me, and had lava lamps and model spaceships and I thought it was soooo cool. So when he asked me to play a little game with him, and whipped out his dick and told me if I kissed it I'd grow my own, I thought it was okay, and fun, and I did it. And then I felt bad, and I hid it from my mom, because I had done the bad thing, I had willingly participated. I was bad. When I finally broke down and told my mom, she told me it wasn't my fault and that had helped a lot, but the shame still fucks me up. So, yeah, shame-based responses to this are fucked up, they'll fuck her up, and fuck anyone who says that because she was a 'willing participant' it was something she should be punished for. HOWEVER, absolutely monitor her internet usage.
I have been banned from the computer (and therefore internet) for a month or even more. It sucks and it's really shit, but it's not the end of the world. And since she's still a minor, her mother has the wherewithal to make that decision. Now, that needs also discussions on what happened and why it should not happen again, without shaming your sister. But it needs to be talked about. At that age having such an older man text you and pay you attention can feel romantic and exciting and special, and you can ignore the odd little feelings telling you something is off. Maybe it feels like shame to you, so you ignore it because it's obvious what shame it is. I've certainly been in that situation myself, and no one really noticed or helped me. It might be worth it to talk to your mother as well and to see how she is feeling. Yes, she is an adult, but I cannot imagine finding that out would have been easy. Partners generally take it as a personal failure when such things happen. My own siblings are boys and they're 14 and 11. Banning either of them from computers won't help much if they have their smartphones. But I would be quite troubled to hear if either of them were sexting with a girl so much older, and me and mom would have talk about it to see what was going on. It's important to validate her feelings about this so she does not clam up and start hiding everything that happens in the fear that she will be ignored/talked over/misinterpreted. I won't address what the other posters said because my opinions about that aren't going to be particularly helpful and are unnecessary besides.
Thanks Everybody, for advice and thoughts. My mom had a long walk and further talk, with both my sisters about predators just as I was leaving for work. So there is that. I'm not sure even if we can turn him into the police as he's 5 states away, give or take and I'm not sure if they know his real name.
A general location and a phone number are actually a pretty good start for this guy's RL information - I think that it really depends on what exactly the law says, and what the rules for pressing these kind of charges across state lines are. Of course, all that's just answering the question of if you can press charges. Whether you should all comes down to how your sister feels, and what she's willing to put herself through. The process of prosecuting this stuff is a long, arduous, shitty one for victims, and many of the laws are woefully outdated with regards to this kind of predation. She'll have to see her predator and recount the entire thing, and every aspect of her testimony and character will be picked apart and cast into doubt by the defense.* In the end, it'll almost certainly come down not to right and wrong, but to some dumb-ass semantics argument about whether this guy's fuckery fits under the arbitrary definition given for some word or phrase in the law.** The guy undeniably deserves to pay for this, and it would be fucking great to do so. But your sister is the victim here, so what matters most is doing what's best for her. *I mean, thank god that defense lawyers exist, because sending innocent people to jail is the shits. But the process does totally, undeniably suck for victims. **Think Rigs, but fifty times more obnoxious about it.