How Strong Is This Strongbox?

Very interesting announcement today, via Amy Davidson at The New Yorker, that the magazine has launched its Strongbox as a site where you can leak documents and tips--developed by the late Aaron Swartz, no less, and Kevin Poulsen of Wired famed, who explains it here.   I am curious, however, about claiming offers only a "reasonable" amount of anonymity.   Davidson does say, "as it’s set up, even we won’t be able to figure out where files sent to us come from. If anyone asks us, we won’t be able to tell them."  Take that, DOJ.