It’s not Notch’s game. He doesn’t work on it, he just liked the idea and brought his friend on board to his newly founded company. He provides the capital, he is basically the publisher in some sense (though he is not CEO of the company he founded), but he publishes a friend’s game.
Notch and Jahkob have been friends for a long long time and Jahkob has had this game idea for a long time. Notch, Jahkob and Carl (Manneh, serving as CEO) founded Mojang with Jahkob being part of the company to initially develop Scrolls.
You're correct that Notch has no involvement with Scrolls (code wise) however his friend (Jahkob) is a co-founder of Mojang, Mojang aren't just "publishing" it, it is their game which has about 30% of the company involved with it.