Don't know who leaked this, but Dianne Feinstein's billionaire husband has had extensive dealings with China - not to mention some illegal land grabs including a borax mine on a state reserve. He's a big-time swindler, hence Mrs. Feinstein is the richest woman in the Senate.
You think he was eavesdropping on Feinstein's husband? That would certainly explain the need to keep it secret.