Rigor mortis sets in after a couple hours.
It seems like you’re grasping at any possible straw you can find, and I’m wondering why.
http://www.encyclopedia.com/topic/rigor_mortis.aspx
it’s simply a learning process:
“...Temperature is an important factor in determining the time of onset of rigor. In normal circumstances and at room temperature rigor is complete in about three to six hours. If the temperature is higher the onset is more rapid — perhaps no more than an hour in tropical temperatures...”
Have a look at Google Images for drowning victims, nicely laid out straight as a board, some of them.