Apple doesn't care about porn on iOS devices, they just don't want it in the App Store. Unless a PornHub app is full of malware, it shouldn't have any problem getting notarized.

App Store Review = Content and Quality

Notarization = Safety and Security

...if it works like on Mac, then I would, yes. It's an automated process and I'm not aware of any content requirements.

>Through a combination of automated checks and human review, Notarization will help ensure apps are free of known malware, viruses, or other security threats, function as promised, and don’t expose users to egregious fraud.

I wouldn't be 100% confident there. I wouldn't be surprised if porn got through, but plenty of other companies have blocked such content under "security threats".