If he’s a demigod or otherwise high in the favour of some god or other, he might be less scared of particular gods. Hades wasn’t very popular among his brothers, so I could see Theseus being bolder with him.

More significant is the human factor of who made up the respective stories and how they wanted to frame him: one as brave against Hades, the other as devout towards the god of parties. His legend won’t have been written by a single author trying to create a consistent character.

Either way, he’s a cunt.