Go look at the replay. The throw was to the outfield side of the bag and Busch almost got his arm taken off by the runner trying to make the catch. That ball needed to be further to his left and if it was, it would have been an out. I don't disagree with the ruling of it as a hit because it was a very difficult play, but Nico botched the throw.
Go to 6:30 in this: https://www.mlb.com/gameday/777482/video/condensed-game-mil-chc-6-17-25