Nonsense. If Cruz and Trump were swapped, I would want Trump to stay in, just as I want Cruz to stay now. [And I'd vote Cruz in a week to give the best chance for a first ballot decision, just as I'll actually be voting Trump in a week for that reason. Both are good choices, but the important things are (1) avoid a second ballot if possible, and (2) have as many anti-Amnesty, anti-establishment delegates on the floor as possible.]
In the real world, I want Cruz to stay in for as long as Kasich does. The conversation changes when there are only two candidates left, and I do not want to risk that dynamic with Kasich. The best situation for a candidate like Trump is obviously being the only one left, but three candidates left is the second best situation - far better than having two left or a large field. Trump and I both agree with Cruz on the most important issues for the next eight years, while Kasich is on the other side for almost every key issue.
Kasich would get more delegates without Cruz in the race. Without Cruz, the convention would therefore have more delegates who are pro-establishment, pro-Amnesty, and more willing to circumvent the primaries. If the convention is 80% Cruz and Trump delegates, we have a much better chance that at least 50% of them will resist establishment efforts to derail the convention and nominate a "white knight".
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?