This should not have happened and it's always so sad to hear about a death like this.
My condolences to his family and friends.
Again this should not have happened.
To many errors were made. 13m kite in 20-25mph.
I'm 225 lbs and go with a 9m in winds above 20mph.
Kiting a storm front is a very bad idea even for an expert rider.
Kiter did not activate his release.
Safety Release reflex (SRR). Everyone should become familiar with their safety release and be ready to activate it very quickly.
Unfortunately it is not like the breaks of your car. We use out breaks both in emergencies and in normal driving. You only need the safety release in an emergency... that is why I say it is very very important to know your release very well.
See this thread for more on SRR:
Another thing that is important. newer riders should be using bigger boards and smaller kites.
Bigger board requires less power so a smaller kite can be used. Less power results in better safety.