The weak link in a hi-line is designed to do exactly that - break - so that any entanglement or snagging doesn't put an undue load on the hoist cable and snap the wire or damage the housing/drum or even pull the hook off the wire.
The fact that this one recoiled towards the rotor isn't unusual, we had one that did go through the rotor after the hook itself snagged a boat rail and then came free under tension.
This incident would be considered a Normal Operating Hazard for military SAR.