In the meatspace, if a suspected or known criminal was always hanging out in a certain small corporate office with only a few people then they might wiretap the whole building, even though the other workers are not necessarily involved.

From there they might be able to subpeona the personnel records for that small group of employees even though neither the corporation nor the "extracurricular" group those workers are involved with are even charged with any wrongdoing, based just on the personal wrongdoing of one of those workers and that one's association with the others in his building.

That doesn't mean there's no shenanigans going on here (I haven't looked at the article yet) but Wikileaks being formally accused of a crime is not compulsory to getting individual subpeonas in general.