Because that Russians wanted to keep it secret what they did test with. Probably because they don't like their boxers beaten in the shady gambling world.
Point to note, the athletes did not undergo a testosterone examination but were subject to a separate and recognized test, whereby the specifics remain confidential.
The International Boxing Association, previously known as the Association Internationale de Boxe Amateur, is an international sports organization that sanctions amateur boxing matches and awards world and subordinate championships. IBA consists of five continental confederations: AFBC, AMBC, ASBC, EUBC, and OCBC.Wikipedia
