Trump and Cruz together will have the vast majority of delegates by the time of the convention. That means the Republicans voters decided that either Trump or Cruz should be the nominee. To reject that decision is to insult the voters. Referring to the rules or the rules-to-be misses the point. For the Republican Party to reject the voters' choice is to risk receiving the wrath of the voters.
I hope the GOPe steps back from the brink and decides not to run its party like a third-world dictatorship. Unfortunately, it is too arrogant and so Trump and Cruz will have to stop the GOPe. If they fail, then the People should punishment the party with the goal of destroying it.
Your post is spot on. Good points.