Snake of the Festival was imprisoned long before the Coffin Weaver's activities during the Middle Ages. Snake was defeated by an alliance of all the strongest Guze Kings plus Alastor around the time of ancient Babylon. They put him away because he was too tough to kill, and his crime was trying to change how existence works in both worlds.
Snake admires humans and he's the God of Creation, so he hates how Tomogara sneak into the real world and kill humans to achieve their goals, and likewise hates how the Guze Kings use Flame Haze as some kind of hobby to kill the Tomogara. It's fucking stupid.
So he wants to change the nature of existence for Tomogara and humans so they won't have that predator-prey relationship. The problem is it's risky and the other Guze Kings don't want that risk.
With Yuuji as his ally, he's virtual invincible right now. Near physically impenetrable body, a floating fotress, three unbelievably powerful Guze Kings as worshippers, hordes of followers, immunity to magic, unlimited offensive power, the ability to hide his presence and detect the presence of even the smallest amount of existence, and a physical Stand as powerful as a very strong Guze King that can replicate itself a million times and acts as his personal bodyguard.
This whole awesome shit just got sacrificed for harem visual novel love triangles.
Fuck JC Staff, and fuck Japan.