What did the helicopter do wrong, anything? If it was engaged in a Search and Recovery mission I would say it was highly unlikely from the information in the few accounts that I could find online.
What did the kiter do wrong? Lots based on what info is available. I hope they spare themselves embarrassment and possible harm to the sport by not filing a complaint.
- Keep your ears and eyes open, if a helicopter approaches, ease your kite closer to the water as it passes. You don't want to catch your kite on the skids or in the rotors. If there is helicopter traffic in the area, you need to be aware of it along with boats, other kiters, windsurfers, kayakers, surfers, etc. etc., you DON'T throw a jump anywhere near it. Stay aware and properly respond in advance. This should be second nature to all kiters.
- If you choose to jump in water so shallow as to cause an injury like this, you can only blame yourself when it goes wrong. This time some rotor wash stalled the kite, usually it is a lull, steering error, lost foot strap, whatever but too many kiters have had far more serious injuries than this from boosting in the shallows.
Helicopters trail rotor wash behind them extending downward towards the surface. If your kite encounters one, it may stall and drop you like a rock, cause your kite to drop momentarily or worse it might just tie the kite in knots. Just like boat wakes, you need to expect they are there and watch out for them. They can seriously disturb the air below them even if they chopper is flying well above kite level.
The helicopter generates a ring of disturbed air which leaves as a vortex extending behind and below the chopper.
The vortex is that loopy colored stuff that will drop your kite pretty quickly if you encounter enough of it.
Kites and helicopters don't mix, work to keep them apart for these and still other reasons. It isn't hard to do if you are paying attention.