I understand what you’re saying, but if Cruz did the honorable thing, dropped out, and asked his delegates to support Trump how would that NOT utterly block Kasich and the GOP-e?
Asked? That depends on how loyal the Cruz delegates are. Asking is not binding, and most delegates would not take it as such. It's not even terribly effective unless Trump simultaneously announces that his VP will be Cruz.
At the very least, staying in until all delegates are selected helps because that gives Kasich (a pure establishment candidate, or a bit left of the establishment) fewer delegates. At the very least, staying in until the Convention rules are approved helps because that gives Cruz delegates a personal stake in seeing that the rules protect Cruz, and the rules that would protect Cruz are almost exactly the same as the rules that protect Trump. Once the convention rules are chosen, my view on Cruz staying in may change, depending on those rules. At least for now thogh, both Trump and Cruz have much better odds with Cruz in the race.