The massive black hole is a result of the Green Sun blowing to smithereens and the canon relevancy isn't that big of an issue or a problem for them, the passive EXP gain and the weird glitch of the game from them triggering two game ending cutscenes at the same time is the "real" issue lol (it's like if one person skipped Asgore's fight in Undertale while another tried to still fight him. You'd trigger two cutscenes in the game that would make it just inexplicably crap itself. Sburb isn't a game that EVER "crashes" as in there's no way for them to just stop playing or turn it off, so it just keeps going forever until the players all die or they win.)