The next part of the Creative Development Q&As are out, a portion of which you can read below:
Question: What happened to the nanite serum used to de-infest Alexei Stukov? I ask, because this is all I could think about during the final Colonist missions in Wings of Liberty. Raynor must choose to side with either Selendis to destroy the infested colonists, or Hanson in the hope that she will find a cure . . . but a cure already exists. It has been around for years. Selendis comments that the only cure for infestation is purification by fire, which is confusing because she was part of the Protoss force that aided Raynor during the mission to save Stukov. But even if that weren't the case, why didn't Raynor mention the serum or Stukov? How could he possibly forget such an important event? He did not mention the serum, and if he does choose to side with Selendis, he even agrees that there is 'no other way.' It's an obvious plot hole.
Answer: Raynor is faced with a populous colony where a major infestation is about to break out, and a Protoss fleet is poised to burn it to the ground . . . and he should ask about a serum that was used on one person years ago? A serum that the Protoss fleet would not have with them, would not have a way to acquire or deploy in any kind of timely fashion? A serum that the commander of said fleet is clearly not interested in using? One that the Zerg have likely evolved an immunity to anyway? I respectfully disagree with the assertion that this is an obvious plot hole. As plot holes go, it's incredibly subtle. ;)
For the full Q&A, click here.
Battle.net - StarCraft II Creative Development Q&A: Part 9