Yes, I remember that old magnetic tape could go brittle, but I’ve never seen it break like glass, which is what the author seems to be claiming.
Perhaps the tape snapped when the make-up feel fell off the spindle. That would have required a single splice to fix.
I think someone’s exaggerating.
The closest I’ve come is seeing 1/4” on a machine with a run away reel motor that got stuck in FF or RW whipping itself into a few small pieces. But it involved a highly unusual combination of factors. Repairing it only involved a razor blade for the purpose of trimming the edges of the splice, though, the pieces were just stuck together in whatever irregular shape the break left them in.
But, yeah, no shattering. The author’s padding the story.