All that mystery for John Harrison? I don't know...I think it might be another diversion. Otherwise, JJ was being completely ridiculous by keeping the name hidden for so long.
Unless it's not actually his real name and merely a pseudonym he goes by throughout the movie? (it's not like Darth Vader was ever directly addressed or billed as Anakin Skywalker in the original Star Wars trilogy)
Hell, he could even fill the Shinzon or Sybok profile, in that he has a particularly personal (initially unrevealed, presumably) connection to one of the characters or is connected to a well known character introduced in the prime verse.