Why would anyone even think Spock's body was there? By all accounts it should've burned up in the atmosphere. Even David and Saavik were surprised to find the torpedo tube. And when Saavik announces to Kirk that there is "a certain Vulcan" there, he seems surprised.
Well, it never made sense to me that the Enterprise crew jetisoned Spock's body at the Genesis planetoid in the first place. Why wouldn't they keep the body in the Enterprise morgue, and deliver it Spock's family/Sarek, or at the very LEAST deliver it to the Vulcan Starfleet representative, for a proper Vulcan burial/ceremony?
And they gutted a torpedo tube to place the body inside it.... why? On a starship with hundreds of crew members, a medical bay and the ability to perform surgical procedures, you know they had coffins on board. Or at the very least, the ship's replicators could create one as needed. The torpedo seems to be a plot device, just so they could shoot his body into the void. Unless this was standard Starfleet procedure (to jettison dead crewmates when on a mission, when away from a Starfleet member world or space station for an extended period of time).
...And then there was NO representation of Spock's Vulcan identity at the funeral. Kirk spoke briefly about how HUMAN Spock ultimately was. Amazing Grace was played, on the bagpipes. Which is a Christian, Western Society tradition (I know, bagpipes come from Scotland/Europe). Amazing Grace is a 100% relatively modern Christian song that speaks about overcoming life's troubles with divine help, and ultimately the promise of eternal life in Heaven with God. It would be highly inappropriate to use this song at his funeral, UNLESS:
1) Spock had converted to Christianity, or...
2) They lyrics had been changed over the years, to remove the religious connotation, or...
3) Spock just liked the song and would have wanted it to be played at his funeral (we later learn in ST 6 that Spock had a painting of the Expulsion from Paradise in his private quarters... he referenced it as an Earth myth that reminded him that all things end).
...And even though the torpedo tube did not somehow disintegrate on atmospheric entry on the Genesis planetoid... it didn't have thrusters to help it decelerate or even "land", and it would have CRASHED into the ocean or land, and certainly been shredded to smithereens at impact.
...And even though it DID survive its crash landing, the corpse inside most certainly would NOT HAVE remained intact. It would have been green fleshy goo and pulverized bones inside the torpedo tube.
..And since a Vulcan's Katra was a known "thing" in the Vulcan society, then the only way Sarek would have known to seek Kirk and read him the riot act would be because it WAS commonly (or at least, not infrequently) acted upon to somehow preserve the deceased Vulcan's mind/spirit/essence. But there's no indication that Spock's Katra communicated with Sarek for Sarek to be aware of what was really going on... because Sarek didn't know any of the details. Kirk didn't know what Sarek was talking about, which meant that probably NO HUMAN would know about the Katra... which means that Sarek should not have been upset with Kirk for not knowing about some private, ancient Vulcan ritual that was never discussed with outsiders.
...and exactly HOW was this used in day to day Vulcan society? Grandma is on her death bed, so she does a quick mind meld with a family member to pass on her spirit... and then what? Did the recipient now have their relative's mind living inside of them?
The closest I THINK we got was when Sarek mind melded with Picard, and then Picard allowed Spock to mind meld with him and experience Sarek's sssence/mind/Katra ??? So, did Picard possess the mind of Sarek, and then hand it over to Spock?