Worse than Biden. You can't win a General Election if you can't appeal to African Americans.
Biden did worse than Hillary with them, hell he did worse than John Freaking Kerry and had to rely much more on mea culpa oldies and college educated whites to make up that difference.
I'd call it a wash at face value, but that doesn't account for what Trump could do...which to Biden's credit, Trump actually flubbed on.
The AP Votecast results (which most agree are more accurate than the Edison results for 2020) say otherwise.
Anyway, Buttigieg would have ACTUALLY done MUCH worse. And that would be enough to sink him. Never mind he probably doesn't stop the bleeding or recover with some rural voters the way Biden did. He MIGHT do about as well with suburban voters and college-educated whites, but that wouldn't be enough by itself.