This didn't form part of the prosecutions case at trial or appeal hearings.
That doesn't man we should ignore it where we are searching for the truth.
It was not part of the trial because the experts missed it. It was part of the appeal hearing but the COA refused to consider it because they determined even though it is credible it was not new in the sense that it could not have been recognized at the time of the trial had they used due diligence. It wasn't based on new science. There are 2 ways to view this
1) Jeremy already lost so it would add nothing to the equation to consider such evidence so they decided to make themselves look good by saying it didn't qualify as new but if the defense put on a stronger showing they actually would have considered it.
2) They genuinely decided to follow the law and not permit new evidence that the prosecution could have used had they used due diligence.
The legal significance is as follows:
If they had allowed it then:
The defense would need to refute the new evidence in addition to the evidence presented at trial in order to get the verdict overturned.
By refusing it:
The defense only needs to overcome the evidence presented at trial in order to get the verdict overturned and if overturned then the prosecution could use the new evidence at a new trial but would not be able to use to prevent the conviction from being overturned.
Also, even though they said they officially would not consider it that is still something that could be in the back of their minds and still find its way into their thinking regardless of what they claim.