[quote=@Double Capybara]
[@Vec] I understand that, but as I said, some systems like The Occult had direct influence of the god.
[/quote]

The properties of The Occult were programmed into the Universe and are an intrinsic property of objects and words and rituals, thanks to the Codex. Mammon was the biggest practitioner and the author, and if he were around he could be the focus of many Occult rituals, but he was not its power source. Mammon defined the set of all possible outcomes for Occult rituals when he wrote it into the Codex (probably not explicitly, but by defining a comprehensive set of rules he, by extension, defined all possible outcomes), and unless these rituals specifically required his present existence (which was not implied in the wording of the creation post, so that would be a niche case) then they would continue to work.

P.S.
[quote=@Double Capybara]
[@Vec] That was my impression but I could swear there was a mention of them in that Rtron way before he took him to the plane of madness.
[/quote]

That same post in which Mammon creates the Occult he also makes a little demon.