The Kelvin timeline established in Star Trek (2009) branched off from Trek's prime timeline due to the actions of a Romulan named Nero (Eric Bana). With a supernova about to destroy Romulus, Ambassador Spock came up with a plan to save the planet using red matter. Unfortunately, Spock was too late, and his ship got pulled into the past, along with Nero. Nero emerged first, in 2233, where he encountered and destroyed the USS Kelvin, setting off a series of events. While Leonard Nimoy's presence makes sense, a cameo from another TOS star would have been more difficult to explain.
Nichelle Nichols Almost Played Uhura's Grandmother In The 2009 Star Trek Movie
Nichols Discussed The Possibility Of A Cameo With Director J.J. Abrams
While speaking at Supernova Pop Culture Expo in 2008 (as reported by TrekMovie.com), Nichelle Nichols revealed that she had spoken with director J.J. Abrams about a possible cameo in his upcoming Star Trek movie. According to Nichols, Abrams suggested that she could play the mother of Lt. Nyota Uhura (Zoe Saldaña), to which Nichols replied that she could play her grandmother. Abrams appeared to be enthusiastic about the idea, but the 2007-2008 Writers Guild of America derailed any potential plans for Nichols to appear.
Nichelle Nichols also remarked that J.J. Abrams did not want a cameo from the actress in Star Trek (2009) "to be a gimmick." Because the majority of the film took place in the 2250s, time travel was the only way Leonard Nimoy's Spock was able to appear. It would have been hard to justify the appearance of any other characters from Star Trek: The Original Series. While Nichols could have portrayed Uhura's grandmother, as Abrams proposed, this would have come with its own set ot problems.
Nichelle Nichols' Star Trek Cameo Would've Been Sweet, But A Canon Nightmare
With Leonard Nimoy's Spock Already In The Film, Nichols' Cameo Wouldn't Have Made Sense
While it would have been great to see Nichelle Nichols in Star Trek again, it may have been one classic Trek actor too many. Because Leonard Nimoy was already appearing as Ambassador Spock, an appearance from Nichols would only have worked if she was portraying the Uhura of Star Trek: The Original Series. Having her portray an entirely different character (even one in the Uhura family) would have been confusing. Star Trek (2009) could have either had Leonard Nimoy as Prime Universe Spock or Nichelle Nichols as Uhura's grandmother, but it could not do both.
As J.J. Abrams said, he needed a solid reason to cast any TOS actors in his Star Trek film. The film's plot revolves around Nero, Romulus, and Ambassador Spock, so Leonard Nimoy's appearance was necessary. But if too many characters were popping up across timelines and time periods, it could have begun to feel like empty fan service. In the end, Nimoy's Spock was a nice way to pay homage to TOS, while making Star Trek (2009) fit in with the rest of the Trek universe.
Playing Uhura's Grandmother Would've Given Nichelle Nichols A Fitting Star Trek Finale
A Cameo Would've Been Nice, But Uhura Is Nichelle Nichols' Legacy
Although Lt. Uhura has always been a great character, she was often relegated to the sidelines on Star Trek: The Original Series. There were only so many ways Nichelle Nichols could deliver lines about hailing frequencies, and there were many times when it would have been nice to see her get more to do. Thankfully, both Zoe Saldaña's version of Uhura and Celia Rose Gooding's Uhura in Star Trek: Strange New Worlds have brought new depth to the character and made her even more of a hero. But neither of their performances would've been possible without Nichelle Nichols.