Seeing as the subject of the sentence is the pig organ, it's saying the organ is the one doing the surviving and only tangentionally mentions the person surviving by calling then living. I (and presumably we) only come to a different interperetation because I have the context that the latter is the important bit. If I give some other similarly structured sentences but without context, how would you interperet these?
- This is the fastest Alice had driven since Bob broke the speed limit.
- This is the oldest tree still standing in the burnt forest.
- This is the most stable chemical additive to our long-lasting concrete.
Without context, to me these examples sound primarily about Alice going fast, the tree being old, and the chemical being stable. But if those appeared in articles about traffic law, natural disasters, and sidewalk design, then these phrasings might be less ambiguous if flipped (as another commentor pointed out).
Well, the pig organ could fail immediately, causing the person to go back on dialysis for 6 months. That person would've also lived for 6 months after a transplant.