The impulse to do it is kind, and good-hearted, but in practice, I think all it's going to do is give some poor cast member the job of clearing it away several times a day.
Remember, this is Disney, where presentation is everything and it's all about keeping the guests firmly away from the outside world, and immersed in theming. They won't be allowing a display to call every passing guest's attention to the fact that a guest was killed by an alligator at that spot.
I think stopping by for a moment of prayer or reflection would be nice, if anyone's so inclined.