to get my thoughts in order… Sollux lives in a giant computer, which Andrew hints at in the commentary for his introduction: “…he was built to be little more than a serviceable part of a big machine.“ when we first see him, he’s living in a room filled with beehouse mainframes; computers that run on the labour of worker organisms. then we zoom out a little bit later and see that Sollux’ hive is literally just part of a much larger version of that beehouse mainframe.
the computer serves a dual purpose in Alternian society, being part of the machine that keeps trolls hivebent, trapped in a simulated version of reality, but also the one link trolls have to the world outside their simulation, something that connects them to other trolls.
so Sollux severs the top from his computer, and in doing so severs his hive stem - or rather his brain stem. when Karkat says that having one’s “LOBE STEM CAUTERIZED” disconnects one from the primary emotions that drive interpersonal relationships, he’s really warning that destroying your computer will cut you off from the world. and just as Karkat’s neighbours, separated from him by porous cranial plates, can be seen as his otherselves, the workers in Sollux’ beehouses should be thought of as miniatures of Sollux himself; when the Sollux gets mind honey on him, he stares at the stains on his hands like Dave staring at the stains of his own blood, because whatever those machines run on is the equivalent of Sollux’ blood.
so the hive, as a macrocosm of the computer, has a twofold nature; Sollux’ hive stem isn’t purely connective, nor is Karkat’s lawn ring purely disjunctive. whether one allows the hive to be a prison or a gateway relies heavily on the individual: Karkat’s antisocial temperament and fear of interaction with his otherselves causes him to reject connection with others, and to insist that Jade turn off her own window into her other life. but just as the Yellow Lawn Ring was a boundary between the pre-scratch and the post-scratch, it was also the pathway that allowed connection between the two.