Oi vey, this one again.
Okay, far as I know there is nothing -official- stating that you cannot have a Forsaker/Psion.
Very similar in fact to nothing -official- stating that you can't have a Half-Fiend Trumpet Archon, or PCs with Divine Ranks, or Paragon Half-Dragon Black Pudding with 40 levels of Cleric. You CAN.. but it's twinkish, and lame.
Taking a character class that is totally centered around the rejection of the supernatural because it a a crutch and a corruptive influence.. and then giving him levels in a class that is centered around the devopment of the same supernatural powers he hates.. yeah. Bad Idea.
I -heavily- suggest against it. Sorry if I come across as a bit harsh, but this is a peeve of mine. It's come up before in my gaming circle.
*storms off to grind his teeth together*