Thor without his powers hangs with Captain America. Unenchanted Uru is likely still a tougher substance than what Leonidas is sporting.
So overall Thor is going to mop the floor with him, really badly. Not to knock a fellow Spartan, it's just Thor's still ridiculous. Even movie Thor can apparently mop the floor with some of the most well trained personnel on the planet solo and requires six or people just to restrain him.
Maybe if Leonidas uses his slowmo powers he might do a bit better.
If there are no morals then thor just hits the ground once destroying the planet and Kid Flash dies. Thor can swing his arm 3x faster then light. He can hit the ground before or as Kid Flash gets to him.