Becoming a Force Ghost isn't really a Medius technique.
No, becoming a Force ghost not. Becoming a Force ghost without leaving a body behind is. (At this time. I think all Jedi who die ingame, even those who appear as ghosts, leave a body behind.... except Revan, of course
So, he's more crazy than Noxy. Oh joy
In fact this is based upon some kind of crazy philosophy known here on earth: Solipsism. If you think about it, you can't prove that anything exept yourself exists. So why believe it does?
But Solipsists are so lonly