Thinking about the case, I believe the AIDA Board, Comissions, and the Assembly should discuss it and set clear rules what to do in a case when a competitor dives, and the dive needs to be interrupted immediately for safety reasons. Perhaps using a laud UW speaker or a siren, and/or continusly pulling on the rope could be used to signal the competitor that he has to interrupt the dive immediatly and return back. Never mind if more competitors will be diving in the same time - it is better if they all have their dives cancelled (or have to repeat them), than losing a diver. If there was a safety diver with a scooter ready, he could have stopped Michal. But apparently there are no procedure, and no drills for such case, so even if the scooter was there, it is a question whether they'd react quick enough if the procedure was not trained.
EDIT: and in the same time, also for many other cases, I think there should be a way for the freediver to send a signal to the surface in distress. Not only in case of losing the rope, but also when entangled, having some medical problem, or in many other cases. One possibility is repeatadly pulling the line (if not lost) - but as long as such signal is not standardized and tought to both competitors and safeties, it risks not to be used, or not to be interpreted correctly or quickly enough. Some electronic singalling might be even better, and there are devices on the market that can even give its position and depth under water. I think it would be worth of investigating its use for competitions and record attempts (well for trainings finally too).