Well, I don't think Horn is going to change his testimony, and I don't think he was equivocal at all. He said he was sure the bullet would have gone through the brain.
I think the state would have had a little easier time of it if Horn had concluded that the gunshot was first -- and that's a pretty good indication that he did not tailor his testimony for the benefit of the state. If the state could theorize that the gunshot came first, then it's really easy to see that Jodi went above and beyond what would have been necessary to defend herself, even if a jury could somehow imagine that such defense was initially necessary.
However, the state is going with what the only evidence is, and that is the scientific testimony from Horn. And as many have said before me - it doesn't matter because it's clear that there was some time that Jodi was continually stabbing Travis and that he was trying to defend himself.