I don’t know if the story is true or not, but I can see this happening with my kid, lo, those many years ago. Mom is trying to unload the dishwasher, trying to keep the toddler in the same room so he doesn’t run off and do some damage elsewhere, he tries to help, I say, “No no, honey, don’t touch the—Ooooof!” This is exactly what would have happened. We had similar accidents, though I’m thankful nothing involving knives.
I get hit in the legs with wooden swords and plastic light sabers all the time ;-).
This story seems reasonable enough to me, especially if (its being Florida) the mother was wearing shorts.