A lot of famous people started out doing stupid things in front of friends or video cameras. True, it would be better if he pointed out up front that it was an illusion, but its not quite grounds for chlorinating his genes.
As for your kids on camping trips, many of the lessons I was taught about safe use of knives and fire (either in the woods, the kitchen or the lab) were strongly re-enforced by scorching or slicing parts of my anatomy.
Experience is the best teacher because we tend to remember her lessons.
On the other hand, just because he's a magician doesn't mean I wouldn't laugh my head off if a trick went bad and he did end up with a knife in the hand. I mean, thats just hilarious.
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A gentleman should always be able to break his fast in the manner of a gentleman where so ever he may find himself.--Good Omens