@anderscs @kino @admin I'm not sure if they could mine it as such, the data isn't on their server.
Sure they could parse posts to gather information - but this is a public forum, so anyone could do that really.
Plus there's rate limiting. My instance only allows 3 timeline requests every 5 seconds for unauthenticated users - so actually gathering any sort of useful data would be a long task.
In the end I'm sure if they ever tried anything suspect then instances would block federation with them and that'd be the end of it.