Hi Joey.
I don't know what this guy means by 'picking the most epistemologically productive' worldview. But I can think of a few things he might mean.
He might mean 'the one that most appeals to him'. But if that's the case, why can't the Christian be justified in picking Christianity on the same basis? So I doubt he means this.
He might mean 'the one that best explains his experiences'. But if that's the case, I don't see how he ends up with realism, since both solipsism and realism explain the experiences we have as human beings equally well, and there's no evidence independent of either of these worldviews that favours one over the other.
He might mean 'the one that yields the most knowledge'. But, if that's the case, I think he's begging the question, since what's at stake here is whether there really is an external world for us to derive knowledge from in the first place! In other words, you have to presuppose the existence of an external world to arrive at the conclusion that realism yields the most knowledge of it. And, if this kind of reasoning is valid, why not presuppose the truth of solipsism, and then justify it on the basis that it's the least deceptive of the two worldviews?
The fundamental point I think Craig tries to get across in his exchange with Wolpert isn't, of course, that we should all become solipsists. Rather, his point is that we all believe things that can't be justified on the basis of evidence. So, even if it turns out that there isn't any decent evidence for Christianity (which I don't think is the case), the Christian can still be rational in maintaining his beliefs.
Take, for instance, the issue of morality. Moral judgements clearly lay claim to some kind of knowledge. But what evidence is there for making these kinds of judgements? What evidence is there that, say, senseless murder is evil? In the end, most people would probably end up saying something like 'I just know in my heart that some things are right and other things are wrong'. Fine. I wouldn't disagree with them. But why, then, can't the Christian 'just know in his heart that God exists'?