I think Cruz never had a chance at a first round win and the GOPe never needed a poison pill.
The Cruz missal thwarts their plan to siphon delegates from Trump, does not advance it. Re-think your conspiracy theory.
Rethink your own conspiracy theory. If Trump is denied on the first round, then the delegates are free to vote for whomever. It won't be Cruz. Cruz served his purpose which was to deny Trump a first round victory and open the convention to the machinations of the GOPe.
The candidate will be romney, or kasich, or ryan. They may even drag jeb! back in.