(Henri, you're in copy of this again, because first time I did a Reply instead of Reply to list/all. Sorry.)
Oh I definitely know the sources aren't officially accessible. By the way, I had copies of them (my QIC tape) when I was a student. I still have the QIC.
It's the common example that I use to tell people that opensourcing software makes it more secure because the good guys have access to the source code at the same time as the bad guys, which gives them a fair chance to fix bugs before the bad guys use them.
With closed source (SunOS, VMS...) the good guys don't have access to the source code... but the bad guys will always (either by paying somebody enough to make a copy for them, or by finding them on some non legitimate place). As a student I had the source of SunOS (4.1.3) but also VMS (on a few TK-50 tapes).
For me, that vetusware site is certainly not legitimate... but since I have the QIC tape at home, I just used it as an easy alternative to having to get the hardware to read my tape back in working order...
I certainly do not consider it a legally approved way of distributing code which is, as we all agree, NOT open source.
Gilles