ohhhhh… by mistakenly understanding the “yellow yard” as a “YELLOW LAWN RING”, Karkat is in fact positioning the crossing of the yard as the irreversible crossing of an event horizon!
this aligns very neatly with my prior assessment on the matter - that the lawnrings separating suburban homes are emblematic of the borders separating different realities - and completes one of Homestuck’s classic chains of iterative escalation; just as each home is surrounded by a lawn ring and each session of Sburb is surrounded by the “Furthest Ring”, reality itself would naturally have an even Furthester Ring insulating it from what’s outside!
but I can’t help but think even further back to the synonymity between the “yellow lawn ring” and the comic’s other ‘yellow rings’. if the yellow brick road is a black hole’s event horizon, then seemingly we have to make the logical leap that the yellow Rings of Life and Void are also in their own ways the event horizons of a black hole. so, huh?