They're not just suing Cryptsy for having poor security, they're claiming that Cryptsy is actively involved in the theft and that the "online cryptocurrency trading platform" is just a guise.
I don't think they have a big chance of winning this ^^
This action seeks to compensate Plaintiff for the theft of his Bitcoin, an act of complex design, perpetrated upon him by Defendants under the guise of an online cryptocurrency trading platform created and deployed by Defendants specifically to induce the public, including Plaintiff, to transfer Bitcoin to Defendants for Defendants’ later misappropriation and use.