Throw out-of-bounds pass negates ineligible receiver?

[ricknau]

New poster here. Saw a strange (to me) call yesterday in the FL State v NC State game. I can't find a rule book anywhere online without buying it. Found this forum and figured you guys could validate or overrule the call. What do you guys think?

QB scrambled outside of tackle box then threw ball out of bounds to avoid a sack. Flag for ineligible receiver was picked up because as ref said, "QB legally threw the ball away". Really? Seems to me that this should be considered an incomplete pass. Why should the offense be let off the hook?