By transporting Bosch back in time, the Shivans had a menacing plan:
Admiral Bosch accidentally kills William Shatner with his 5,000 pound laptop therefore ruining the Star Trek franchise in the 20th century. However, this also meant that in that dimension where he was thrown to, FreeSpace was never created by Volition (and George Lucas also reversed his decision to think of Star Wars).
Bosch, ashamed of the horrible devastation that he caused, eventually went crazy and sent the Iceni in a collision course to Earth at 2012, creating a massive earthquake which wipes the planet of humanity.