Actually, the “quiet period” is limited to the data. They just have one product with anything going on so for you, it seems like they have never, ever said anything. But that’s not true. They talk about Sawston. They will release their quarterly shortly.
It’s not “self-imposed” it is the industry standard for trial results and avoids trouble at multiple levels. Therefore it is not actually self-imposed. That bulletin board posters say what they say, is another matter. There is no per se rule, but the law does not always come with simple instructions.