Apple isn’t interested in restricting your access. They’re interested in brand association. Nobody conflates Apple’s Sari browser with adult content.
This is about Apple producing or licensing content. They don’t want their name, logo, or brand associated with certain content. It will limit their ability to ship content like Game of Thrones, but it’s not about blocking content produced by third parties.
Social networking sites for BDSM sexual minorities are banned from the app store. Sites like Comixology frequently delist books from their app because they're terrified of Apple's arbitrary and capricious censorship deleting them off the platform entirely, despite the fact they don't even accept payments via any Apple systems. They block sexual health education apps.
Apple is very interested in restricting people's access to sexual content and to sexual minorities that Tim Cook isn't a member of.
And just because this was a business decision doesn’t mean it’s not a moral one—they’re emphatically against you using your own device to your own ends.
If they were emphatically against you using your device to your own ends, they would do something in the browser.
I can't say I care much about their intentions. I can say that they are preventing me from using my device very effectively.
Restricting people to the app store where they get a cut of all sales is a business choice, not a moral one. They get more money when you can only buy stuff in the way that gives them money.