Also the Minotaur just might not be strong enough, depending on what the labyrinth is made of, given that its purpose in the myth is to keep the Minotaur trappe

Also the Minotaur just might not be strong enough, depending on what the labyrinth is made of, given that its purpose in the myth is to keep the Minotaur trapped. He's half man, half bull, which makes him a lot stronger than a human but AFAIK bulls can't just bust through stone walls.