I imagine at some point in the convention a vote is held to determine that the candidates are actually constitutionally edible for the presidency. Depending on who has the say, that could be when they free up all of Cruz’s delegates.
It seems a bit far-fetched right now, but there are a few things that might happen in the next few weeks that could set it up. But right now, Cruz is useful for keeping trump from getting enough first ballot delegates.
One way they can set the stage is by having one of those sense-of-the-senate resolution things like what they did for McCain. The Cruz supporters will get a chance to argue that the founders intended for an American ex-pat female to move to Russia and have a child with the czar and that child would be a natural born citizen eligible for the US presidency.
Then they ramp up the topic in the msm in the weeks prior to the convention.
I think they’ll drop the other shoe if there is a ‘blue dress’ that exists for the infidelities charge.
I think you are correct that they’ll suddenly become ‘birthers of the first order’.
And, the meme of ‘hated in the Senate’ will suddenly become the coin of the realm throughout the media.
They will DUMP Ted Cruz at the convention like Rumpke Dumps Trash.