Okay, I don't think CCs don't belong in fandoms (though with recent events I understand the sentiment).
I also think if they are going to be in fandom they need to understand some things before they interact or even ask for a dni tag.
Fandom vs. Canon are two different markets. I'm calling them markets both for this analogy and because it's kind of true.
1. While their canon character is theirs to sell (and as a cc, it is a character you have to play when uploading online or else you need to not be in fandom spaces at all) once they successfully sell them people *are* going to take said character and do things you don't like, agree with, or want with that character.
2. You, as a CC are part of the daytime market, in fact you facilitate it. This is the market that is specifically for you and the only market you have control of. Once your character hits the Fandom Night Market, while you're still selling the official one, everyone in that market doesn't have to abide by any of your rules. Because they aren't in your market, they're in a different one.
3. The fandom night market is for the fans. It is not for you as a CC. And trying to enforce the night market is not something you want to do. Yes even with that content that you hate and would rather not exist. So long as no one brings it to your day market (tagging you or putting it somewhere you can see) then you need to be blocking and moving on.
4. The Night Market is going to have both things you like and dislike about your character. While it's fine to interact with things you like and block things you dislike. you as a CC need to understand that even if the person in question made it because they hate you, all you should be doing is blocking and never interacting with that person in the market again.
5. When making a dni tag, which is a grey area for both markets, you need to understand that if you then go and look through it that's on you.
The Night Market should not have to communicate with the Day Market to make their items. If they want you, specific, to interact with something that is the only space where they need to be following Day Market rules because they are specifically bringing it to you to see. And even then, if you don't like it you don't have to do anything with it.
It is not the Day Market's place to tell the Night Market what to stop creating.