The language of that entry is explaining to potential viewers that Squarespace is not responsible for content users may upload, not that they condone or specifically allow/approve of it. This is the important part: You agree to the "Acceptable Use Policy". And what does that policy say? 6.3. Don’t publish sexually explicit or obscene material. It's unfortunate but Squarespace can easily lose Paypal support for example because of Paypal's bad stance on it. The world still has some ways to go towards healthy sex positivity it seems. So if someone decides to report your page and you have adult content, it's likely you'd be taken down.