Bo has tusks.
You see, the developers knew that us fans would not like the forced appearance of Ganon in the game, but they are evil overlords of crime. They kept Ganon in, and the day before
TP was released in America, Titus realized Nintendo's evil plans. They sentthe development team that made Superman 64 to get into Nintendo's evil headquarters. Finding out that it was impossible to program the game to leave Ganon out, the team as a last ditch effort added tusks to Bo, hoping that everybody would think he was the new Ganon; and villain. They just didn't know his role in the story. As a result, Bo got tusks.
That's a true story.
Only, the actual true story is a little more plausible. That's his facial hair.