OK, this is 3 years later than the OP, but I have a different solution to what appeared to be the same problem.
NB: I am not 'happy' with doing anything involving Console or Terminal: it is too easy to do the wrong thing which would be a disaster!
I have an old external HD which had been used as a back-up about 4 years ago. I wanted to clear all the data, to leave it available for reuse by me or others. Using the Disk Utility to do a secure erase was not possible (even the simple one-pass of zeroes) and the same message was displayed as others have reported.
After reading the advice here and deciding that I didn't trust myself to do it properly, I went back to the HD, and sent all the content to Trash. This involved entering my admin password, but was successful. (Yes, I know that means it is still there!)
I was then able to use the Disk Utility to Erase by one-pass with zeroes, although I imagine all other lengthier options would have worked equally well.
I hope that this very simple work-round will be useful for some other non-tech users, and I will be happy for any of the more tech-savvy to tell me of any drawbacks to this procedure.