If anything this hurts Biden worse. There's no buzz on him, a 100 mill in commercials, phone calls, etc.... isn't going to fix that. And when they find out the money's from Bloomberg, forget it. It's still the South, Bloomberg will be seen as a big city Jewish businessman, who wants to take away their guns, sodas, snacks, and fix the election.
Bloomberg holds no sway with the Blacks, he's known as the mayor that gentrified New York and imposed worse law and order than Giuliani.