Search Results: worry about other girls

So I know a girl online is currently seeing a pick up artist but i'm not sure if she knows. I found the pickup artist's Twitter and he has posted several pics of the girl and previous girls he's been with. Usually the girls aren't looking at the camera and seems as if they the shots were taken without their knowledge. While these pics aren't exactly explicit, they aren't exactly SFW either.

In his tweets he has shared his thoughts on them and has even shared private messages he's had with them. Some of these tweets it seems rather mocking, saying they may have mental health issues as they become more attached to him. I guess this is some sort of ego thing because i found out this guy has a small following in the pick artist community. I guess he is some kinda 'expert' that his followers like to get advice from.

While I don't think pickup artist are necessarily bad on its own, the shady tweets are rather worrying.

Here's the problem though, I'm not sure if i should warn the girl who is a stranger. I came across her on Instagram. The girl and the pickup artist follow each other on there. But on Twitter he uses a different name and they do not follow each other. This leads me to believe, the Twitter account and his content there has been hidden from the girl.

So, should I send her a message warning her about it or is it none of my business and I should move on? I appreciate any thoughts and opinions. Thank you.