You are probably a troll, but either way.
AO3 as a side has been built on the core concept of no-censorship. The plattform is run privately by real people on their actual physical servers (rather than using stuff like AWS) and kept up largely by volunteer labor. But keeping those servers online (as technological stuff eats a ton of energy, and also needs to be replaced from time to time) is quite expensive for a site as big as AO3. And this is largely what the money is for they are asking for. And mind you: AO3 does not extort you for money. They ask nicely. You are not forced to pay it. They do not give you some sort of "fanfic limit" you can read unless you pay, like most other platforms do.
It was made, partially, in a reaction to a lot of fics on other platforms (like Livejournal, FF.net, Wattpad) being censored and deleted. Largely just queer smut, mind you. In some cases even queer stuff that did not have smut, but featured stuff like intense kissing.
So AO3 as a side was built to prevent that stuff happening. Creative endeavors are protected in most places of the world by some variation of Freedom of Speech or Artistic Freedom law - as long as the creative work does not directly harm real people (like actual CSAM would, or for example stuff like snuff films, or in the case of written stuff possibly also things that go after normal real people (not celebrities) in an attempt to dox or derogate them through the medium).
AO3 however only protects creative endeavors, so any posting of political declaration that are not any form of fanwork, will be deleted. Because for one AO3 is a fanfiction platform, and also: this kind of speech is not as protected as creative expression - no matter what some Americans will tell you.
But yes, AO3 allows for any sort of kinky writing, because that is literally what AO3 was created to be for. It was created with the promise that it will allow you to creatively express yourself as long as it is not in some illegal way.
And in most countries (and notably: in the US, where the servers are hosted) writing anything fictive is very much legal. Including incest (a writing topic that actually is very rarely forbidden, mind you, given how common it was in history), any fictional depiction of taboo sexual topics.
And it is so silly to me how y'all censorship fans are so up in arm about sexual stuff, but are totally fine with every other Blockbuster movie featuring the heroes killing people in droves. I guess romantization of lethal violence is cool for y'all, but making fictional characters fuck dirty, then it is morally outrageous.
I guess that says all what I need to know about anti-shippers, really. The fact that they fucking love violence so much.