This is the first thing I've heard a Trump supporter say about him that makes sense
Well, that's certainly true. He seems to change his convictions to meet the pragmatic needs of the moment. On the other hand, he's also arrogant, ignorant, uninformed, erratic, and contemptuous of the Bill of Rights. But he's not ideological.
On the other hand, Ted Cruz attributes his success to the fact that he is ideological. There's no contradiction here, of course; the two men are appealing to two entirely different thirds, roughly speaking, of the Republican electorate.
The crucial point is that both of them are out of touch with reality, and neither can be trusted, on the basis of their public behavior, with the most powerful office in the world.
So how about this: Why not nominate someone well-informed, competent, with at least a touch of humility, who is stable, supports the Constitution he'll be required to swear to support and defend, who is conservative but more committed to rationality than to ideology?
In other words, why not nominate somebody who can actually win?
Imagine Steve Martin as the typical Trump or Cruz voter (which doesn't matter) having a moment of epiphany and asking himself those questions. And then imagine his trademark response- the response a Trump or Cruz voter would give: