I explained my theory a few months ago. If Cumberbatch is a shapeshifting Captain Garth or Trelane, his first meeting with Kirk could be masquerading as Gary Mitchell. Kirk then realizes the being is a shapeshifter and tells it: "You're not real. My friend Gary died months ago!" No need for anyone to have read the IDW comic. A simple, throwaway easter egg.
Of course, if Cumberbatch is Trelane, perhaps he is also Koloth?
That comic cover image is so blurry, it's impossible to discern much from it. I tried enlarging it. Allyn
says he saw a clearer version, IIRC.