Hmm, this is an important feature request in my view.
Without this, this program isnt actually deleting any files. They are recoverable and indeed can be done so quite easily.
You will found various source code snippets around with routines to do this to various levels of standards compliance. A small UI option for no safe delete, and perhaps a choice of some of the leading delete standards around for the choice of when it is enabled.
Love the app though!