I believe it is a true story...   The issue was that any early version of the FE tools was set to use the RS04 as a temporary disk when running the system exercisers if it found one.   The author of that error is a friend of mine (and would later become a UNIX guy at Masscomp).  He said to me about it once. he had checked with the DEC OS teams and thought it was an 'ok' because when they did it, none of the DEC OS used the RS04 for permanent storage - the device had been designed to be a swapping device.

From what I understand, the issue was actually short lived, but widely known in the UNIX community.   He told me it the accident only occurred at one site that he knew about (AT&T) and they made a quick change to have it ask before it wiped it out and that verion of the tools was release to the field quickly.  But he was personally wise to UNIX from them on (and it later years would come to love become a UNIX a user although I don't think he ever gave up the EDT macros we wrote for EMACS for him and the other ex-VMS folks).

Clem