What was heroic about the way Perseus responds to the request polydectes makes

Poludectus is the King of Seriphus, he wanted to get it to Danae, Perseus mother. Polidectus also wanted Perseus death, so demands to him to bring the head of Medusa, hoping during the quest Perseus will die, finally he brought the medusa's head but he uses it against Polidectus and turned him into a stone, that's why Perseus is considerate as a hero.