didn't they hinted it already? i believe its his father's doing, he wanted he tian to learn their business, the thug one that is ImACuteLightSaber
They did but they still haven't showed the scenes for that and still haven't explained it (IIRC), but yeah I really don't mind I think the author just wanted to build up the story and will drop the bomb one by one (or in one go) in the future
Old Xian keep edging us about the reason why he tian disappeared