Ginn and Perry use the stones to trade places. Perry goes to help with a problem on Destiny, Ginn goes to report on the Lucian Alliance. Ginn is about to report on a big secret, the big secret Simoen has. Simoen therefore goes in and kills Perry, still in Ginn's body, in order to stop that secret from spilling out. Both Perry and Ginn dies. With Perry being the only person that Rush cares about, sets him off on a rampage.
This theory makes the most sense due to Ginn's limited appearance, 5-6 episodes, the character sheet information about how Simoen is willing to die or kill to protect a secret he's keeping, and how Perry's deal would be the only event might instill that much emotion in Rush.