Sort of curious about this... In the DC comic series, after Spock is revived in Star Trek III (Around issue #9 or so) and participates in the Mirror Universe saga (Where he regains his old self by mind-melding with the Mirror Spock), he's assigned to the science ship Surak and with a few exceptions (such as flashbacks and a team up or two) largely is not involved with the Enterprise crew (Who are on the Excelsior at this point) until the Doomsday bug storyline (Which is sort of a 'reset' button for Star Trek IV as it kills of the Surak crew, messes up Spock's memory again and has Kirk and crew in trouble again fleeing to Vulcan in the bird of prey) and then becomes a regular part of the crew again in Peter David's run. During Spock's tenure on the Surak, Saavik sort of takes his place on Excelsior as science officer. All non-canon of course but still kind of fun. So I'm curious, what was the intent in getting rid of Spock? Paramount's wishes (They didn't seem to have that much control over the Excelsior storyline anyway so I doubt this)? Preference of the writer(s)? Too many characters already (Since the DC comics had a large non-TV supporting cast like Bearclaw etc.)?
Since the comics came out in between The Search for Spock and the next movie, Paramount didn't want the comics to make any major changes in the status quo that existed at the end of TSFS. And the status quo at the end of TSFS was that Spock was alive again but wasn't necessarily back with the crew. They didn't know what the fourth movie might establish, but it stood to reason that if it showed Spock rejoining Kirk's crew, it would probably play it as the first time that had happened since his resurrection. Or maybe it would show Spock having his first major conversation with Kirk or McCoy or whoever since he was brought back. They couldn't know what might happen in the next film. So it was just considered safer to keep Spock sidelined. The Excelsior storyline was also a response to the need to maintain the end-of-film status quo -- they couldn't give Kirk a permanent new command before the fourth movie did, so they had to set up a temporary situation with the Excelsior that would let them keep telling starship-adventure stories until they found out what would happen in the fourth film. Also, it was during Len Wein's run (which overlapped TVH) that Spock rejoined the crew of the Enterprise-A, a status quo that lasted through Mike Carlin's run and finally Peter David's. David only wrote eight issues at the end of Volume 1 (and then came back for Volume 2).