Not a boater, but it seems if they couldn’t get anchor free, cut it loose, and buy a new one.
I think that’s the proper procedure. Anchors are relatively cheap.
Got into this exact situation some years ago. Very heavy winds wouldn’t let me pull boat up to position directly OVER anchor. I took careful note of where I was (off North Fork on Long Island), cut the anchor line and made a tough voyage back to the marina.
Following week, on a calm day, I returned, dragged a treble hook, found my original anchor line, and managed to haul up my own anchor.
Either way, CUTTING THE LINE on a relatively calm day would have left them ALL alive and shopping for a NEW anchor.
Too bad.
Am a boater and ditto your comment. An anchor is nothing compared to 3 lives lost.