This is creating more speculation on Harrisons character on other forums. My first initial thoughts was that he was Arn Darvin, a Klingon infiltrator but this time a augment with superior strength. And with Kirk and crew chasing him to the Klingon home world just confirms my position that I could be right.
And what do you think these two redshirts are looking at on John Harrisons back? Look at their eye positions.