Team Fudd, that incident happened many years ago in LA and the person was using a retriver style reel with 400# FF line and tying to the back. It was not from a spincast reel or not pushing the button, but from the line in his retriever tying off to the bowstring and snapping back. It does not happen with spincast reels and tying to the back with a spincast setup is recommended as it prevents you from drawing and shooting an arrow without the button on the reel being pushed.
For all retriever and hand wrap reels we do recommend using a slide system, but not necessary when using the spincast system.
I also will point out that that particular incident in LA is the only death that has ever been reported from a snapback/retriever incident, although there have been several injuries as a result of the snapback issue.