Don't get why STV needs to be "apocryphal".
It doesn't have to be, of course, but when Shatner gleefully announced his premise for ST V, DC Fontana was asked to comment on her memo from the 60s in which she stated that, in order to preserve Spock's uniqueness in the ongoing TV series, writers were discouraged from being tempted to bring all manner of Spock siblings into the mix. The story probably would have been just as effective if Sybok had been a mentor or teacher, during the years when Sarek had shunned Spock.
After viewing the resulting script and film, Gene Roddenberry was quoted that he "considered parts of the movie to be apocryphal".
GR also disliked the concept of McCoy killing his own father, but De Kelley had appreciated the opportunity to play that scene.