I have been using AI to generate some of my posts in the past 6 days. My intention was to experiment if the forum detects the AI and how far a user can go with AI abuse.
Your intention was probably to continue doing that if you didn't get caught, but unfortunately, you got caught way too early, and then you had to come up with something, which is calling it an experiment to help the community against the usage of AI when the community is doing just fine because most of the AI spammers are caught and given neutral tags.

And it takes some time for the forum to detect the AI posts.
It's not the forum, it's the users who do that, and they do it only because they don't want other users to read posts written not by humans but by bots, and to not allow people to misuse the freedom they get in this space.
But since i get busted is time to share my experience and the knowledge, that way we can build better tools for the AI detection.
Or, "Since I got busted, it's time to fool the community."
i want to make noise to make us all understand where we are with AI, and understand that this is a fight that we can't win.
Wait, I want to quote a part of your post for this point:
Your goal is to produce writing with **less than 3% AI-generated probability** according to tools like GPTZero or Sapling.
Now, the fact that you got caught even after having this line in your prompt shows that AI, at least for now, is losing this war/fight against humans in this forum.

My prompt was really basic and that's why i got detected by the users (I was expecting to get busted by the mods or admins)
Lol, you've literally added everything you could to make the responses as undetectable as possible in your prompt, and you still say that it was really basic. And, mods and admins don't have time to check posts of users, whether AI writes them or not; they only act when the posts are reported. So I don't know why you were having that expectation in the first place.
Can we win the war against AI?
You, getting caught after using a prompt that literally asked the AI model to do everything possible to avoid detection, is proof that we are winning the war, so far.

If a user have a bad spelling and use AI to correct his spelling, is he cheating?
No, but one can make it easier and use a tool such as Grammarly to get help with things like that. I use it myself, and it only helps me correct small mistakes in my writing, and that's not cheating at all.
If a user reads the thread, generates an answer with AI and changes some words to humanize it, is he cheating?
Of course, why use an AI in the first place? If you can't write a response yourself, you shouldn't be in a forum where writing is the fundamental requirement if you want to take part in discussions unless you are only a reader. And, if you are in it only to make money by using AI models and whatnot, you deserve to either get banned or tagged for doing that when you get caught.
If a casino use AI to generate the Image for his main topic is that a problem for the forum?
I don't think so, as long as the generated image isn't an exact replica of another image that already exists, in which case, it could be copying someone else's work, and that can be frowned upon.
I totally understand the problem with AI on the forum, and that's that some of us gets a payment for our post, but if our post have better quality and are more attractive for the people then isn't that better for the casino promotion?
Wait, what? Are you encouraging users to use AI to make posts since the posts can have a better quality, and are you encouraging advertisers or managers to make it acceptable because you believe it can be better for promotional purposes?