Maybe Spock requested solitude for his final moments? After all, it stands to reason he's not particularly close to anyone on New Vulcan. The person he'd probably be closest to is the alternate version of his father, who he had a strained relationship with in his own timeline.And what kind of a world is New Vulcan that lets an old man die alone? Did the Vulcans on New Vulcan blame him so much that they wouldn't be with him at the end?
Though ultimately, the only reason we see Spock on his deathbed alone in this video is because it served the artistic and narrative intent they were trying to convey. They wanted a moment of Kirk and Spock together one last time without any intrusions, and that's what we got.