I think everyone understands that asking people who have never drilled a helicopter water escape to take special actions in an emergency, let alone reach behind them and cut a tether, is just never going to work, certainly not in the few seconds they had. If the floats had functioned as designed, according to the investigation, everyone would have survived. Instead, either because the pilot did not fully activate them, or due to some malfunction, the right float did not inflate, causing the helicopter to capsize.
It's not completely clear to me, but I don't think they ever completely identified the malfunction that resulted in this, but as far as I'm concerned, it's a malfunction in a safety-critical system that caused deaths, and I'm surprised it's not the primary highlight of this accident.