The writers may not have been aware that these would be the final episodes of the series, but they are turning out to be a reasonable (if temporary) end to ongoing plot threads. First there was the apparent resolution of Michael's arc, and then the culmination of McKay's relationship with Keller. Now it's a return to Keller's "Wraith cure" and Todd's relationship with Team Atlantis, which was left ambiguous at best after the mid-season two-part epic.
Apparently, despite his misgivings earlier in the season regarding the genetic therapy and its potential side effects, Todd decided to proceed with the experiments without Dr. Keller to help ensure its success. Things went wrong, to say the least. The result was an episode that wasn't quite what I was expecting from the initial setup.
The writers already went for a "Resident Evil"-esque episode earlier in the season, so another "zombie" installment felt like overkill. After the first act or so, I was resigned to the notion that the team would spend most of its time bemoaning the apparent failure of the gene therapy and fighting off zombie-Wraith. I've mentioned before that the zombie genre is more fun in theory than actuality for me, so I wasn't thrilled.
By the end of the episode, however, it was more about Todd, his reaction to the loss of his people and his vessel, and his future. His conversations with Keller were enlightening, and it's interesting to consider what might have happened if Sheppard hadn't put Todd on the defensive. Not that Sheppard was wrong in confronting Todd about his past choices, but they certainly didn't need the additional conflict at the time!
Although it wasn't my favorite kind of storyline, I must give credit to the writers for making an effort to give Todd and his related plot threads a proper rest. I'm sure (or I can hope) all of that will come back in one of the telefilms next year.