Information inside agencies like GCHQ is strictly compartmentalised, with only the most senior staff having broad cross-programme understanding and access.
In fact, people can be even more cut off from information if they're at a low enough level inside an agency like that because they're forbidden from viewing leaked information to avoid jeopardising their clearances.
A GHCQ staffer working on, say, satellite signals intelligence for one of the regional desks is almost certainly not going to have any useful inside information on the case of someone like Assange.
