New theory on candidate "Protection"
A simple explanation may be this, Harper promises to use the party apparatus to keep the seats of such wingnuts as Rob Anders or Myron Thompson safe from all those in those ridings that might want to unseat them for more sane candidates. In return, those so protected promise to keep their mouths shut.
It make sense, since one of Harper's worst nightmares is likely to be MP's like Anders finding a live microphone and speaking their "mind". If Harper can find a way to effectively shut them up, then one less worry for the micromanager. Nothing can derail the marketing of the Conservative party as moderate than Anders or Thompson spouting off in front of a live mike somewhere. Such an event is surely to be reported in the national press, and definitely in the press in Ontario or Quebec. In Canada's two largest provinces, such reports would scare voters away from the Tories in droves. So much for another minority government, let alone a majority.
So forget theories about internal party politics. It could simply be a deal to keep the crazier members of the party in the Tory equivalent of a witness protection program.