The security audit linked in the article [1] mentions that the researchers submitted several documents via StrongBox, but never got a response.
[1] http://homes.cs.washington.edu/~aczeskis/research/pubs/UW-CS...
[1] http://homes.cs.washington.edu/~aczeskis/research/pubs/UW-CS...
[1] http://homes.cs.washington.edu/~aczeskis/research/pubs/DeadD... [2] https://pressfreedomfoundation.org/blog/2013/10/how-we-plan-...