What happens when you leave a corpse out in the sun for a long time? “SPLURT!”
If you hang em and leave em they will burst.
But he’s supposed to have been walking when he burst. (I wonder if that is the inspiration for the scene in “Monty Python and the Holy Grail”.)
This is very close to it - The shocking part, to the Hebrew mind, is that he hung there long enough for nature to take it's course. Not only was he cursed for hanging from a tree, but doubly so because he was not taken down and given a proper burial. A knowledge of the law and Hebrew culture will open the Book like a blooming rose.