Indeed. He killed his parents to force them to return outside the dungeon...while his parents were effectively acting as the RAM powering the dungeon's pocket universe.
More or less the supernatural equivalent of a segmentation fault/access violation or even ripping the physical RAM boards out of a computer while it was running. Given the explained rules, the humans were shunted outside of the dungeon while Elmia's soul and coffin were stuck in said pocket universe while it collapsed.
Wow i can't believe this ended next chapter, i dead read this sooo long ago on manganelo where it had fucking 9 chapters at first, this some OG trash I used to feed on, 🫡