Evans could ask to separate the case from the other two and ask to have the DNA thrown out.
In theory yes, but I think that is very unlikely given the version of events offered by the defense. I think that would make sense only if (1) the photo lineup is ruled unconstitutional and excluded and (2) the photo lineup is ruled to have tainted an in-court identification and therefore the AV would not be permitted to identify Evans in court (as I said, I don't think those rulings ultimately will be made here); in that situation, then, the ONLY identifying link is the DNA evidence, and it would make sense to seek to exclude the DNA evidence, because that would likely result in the entire case simply being dismissed against Evans (with no evidence of identification by the AV or by the DNA, a motion for dismissal should be granted).
If the case against Evans goes to trial, the DNA results HELP Evans more than hurt him, so I will be surprised if Evans' lawyers seek to have the DNA thrown out in that cirucmstance.