Re: "Not an uncommon story", you mean.
I've head both the platters and the boot story many times from unrelated stories.
Those packs have a pretty solid spindle and the heads pretty much vaporise under the conditions described. I have in my spare room a platter with a deep gouge in the edge from a DEC RA60 that an operator crossthreaded swapping disks in a hurry. The people present recount a sound like a gunshot when he mounted the drive from RSTS. The heads had to be vacuumed out of the unit. The possibility that a poorly maintained or mistreated pack could come apart can't be ruled out though.
As for the boot, the networking consultant Bill Hancock told that story about his own VAX/750 at a DECUS UK convention in the mid/late 1980s and knowing him it wasn't original either.