I'm not sure there's anyone out there who believes Trump had the first thing to do with naming the people on the list, or any clue on who they are and why conservatives would like them - but Supreme Court nominations aren't really something you can give the usual Trump treatment.
Hence allowing you to make that remark about no candidate going into that much detail before, which I'm sure is true. And very possibly he would even stick to that list if elected and required to nominate someone. Which conveniently allows you to gloss over the obvious point that few if any candidates have ever been so unpredictable on most other points. No doubt he doesn't mean most of the outrageous things he says, agreed, but that still doesn't tell us anything about what he actually does mean and what he actually will do.
Which also makes it rather hard to accept the 'candor' and 'at least he's open about what he really thinks' arguments. Either Trump isn't so bad as he seems because he's just putting up an act and smart enough to realize that most of what he says is complete baloney - essentially, kind of a political counterpart of Sacha Baron Cohen, the actor playing Borat. That's the optimistic interpretation. Or he does mean what he says, which means that he is honest and candid, but also pathologically self-obsessed, completely delusional and the worst presidential candidate since Alan Keyes. And then I'm probably being unfairly harsh on Keyes.
For what it's worth, my best guess would be somewhere in the middle - his behaviour is partially an act and partially real, and much but not all of what he says are his genuine views which genuinely do move all over the place because he doesn't have much in the way of political convictions or ideology, or really even much interest in anything beyond his own life, ego and pocket book. But I could be totally wrong - as I've said before, the man is basically a Rorschach test in which any two observers can see completely different things.