I'm not sure why you think any of that is relevant. Educational sites should not require Big Brother's approval, even if they involve biology you'd rather not think about.
Calling BishUK an educational site is how this story even broke daylight. The term Educational site is very misleading in this context IMO. I suppose that you can call hardcore porn educational as well though (if you learn something from watching it then you were educated right?).
Traditional "Sex Education" in school is all about discussing the basics of how anatomy works and the responsibilities and consequences that come along with sexual activity.
BishUK appears to go much further. Discussing in detail sexual positions, techniques ETC. Hardly what most people think of when they hear the term "Education" and hardly appropriate for kids.