If Caliborn is still IN Homestuck and John kinda 'got out of the game', then how come Caliborn can still live and snapchat to John? I mean Calliope created a black hole tend it all...

Well, John got them out of the loop of the Alpha Timeline by the end, they’re free of LE’s influence. Caliborn’s still an asshole and it’s good comedic material to have this glowy-eyed rude ass and the clown bother the Kids on Earth C. Specially if this is not the Caliborn that becomes LE.