I can only assume that the CAA have not actually read the legislation. As I stated previously the word BASE does not even appear in the wording of 216/2008, which, after all is said and done, is the legislative text.
The UK CAA have, and will continue, to form opinions. They are entitled to do so, but the test comes IF they decide to prosecute. They rarely do this if there is any doubt that they will secure a prosecution. The IOM have already stated in writing on their web site that they believe otherwise. So do I.
The regulation 216/2008 (referred to as the basic regulation) seems to me to be VERY clear in it's wording. Even a CAA employee could understand it - if he or she wanted to. The fact is that they no longer make the rules.
There are other threads here that explain the detail of 216/2008 if you care to read.