He is a social moderate but the idea of a flat tax is Libertarian in the extreme.  This will put people off, as will his self-professed admiration for Ayn Rand.  He’s also not given to compromise.

These are the reasons that Harper kept him under wraps even though he was likely one of the brighter bulbs in the party.  (The fiasco with his biker girlfriend was no help, either, admittedly).  And they are the same reasons that he won’t carry an election if he is nominated leader.