"The chances of this person's unique DNA showing up at the scene are a zillion to one!"
"What does that really mean when the sample also contains unique DNA for a hundred other people? Did all of them commit the crime as a group?"
If the DNA is present, it's present - barring any procedural mistakes by the forensics technicians (mislabeled sample, dirty lab equipment, didn't follow manufacturers instructions, etc). Or deceit by one or more members of the forensics team to implicate the suspect.
This is the wrong point at which to correct the problem. When prosecutors are allowed to introduce "science" as their evidence, jurors give this way too much deference. It's the prosecutor basically saying "you're too stupid to understand it, so indulge my appeal to authority" and jurors tend to happily acquiesce. This is why judges are supposed to gatekeep expert testimony and not just let any quack step in and make outrageous claims... and despite their attempts, quacks have repeatedly done just that these past few decades.
If is true that the presence of DNA means essentially nothing, then it shouldn't be permitted to be introduced at trial. Protection from wrongful conviction shouldn't rest on someone having an attorney expensive enough to be able to unsway too-easily-swayed jurors with counter-specious arguments.