Atlantis engaged in a wide variety of insecure practices, just from the publicly available information. Who knows what their server infrastructure and cash out methods were like. Wouldn't be surprised if one or more of the admins was identified or they have info that they are going to be raided or compromised. That's all speculation, of course. Maybe the admins finally read all the papers that came out this year showing how insecure Tor hidden services are and decided to quit while they were ahead.