another way of looking at rapid release of meat might be this :
say you pressure cook meat , and the meat is partially submerged in liquid , or not at all : pressure steamed.
the PC temp is well above 221 F , sea level boiling.
rapid release creates a rapid boil in the pot , and on the surface of the meat . that surface , above the liquid will be dry.
the problem is the dry meat will seem tougher than wet meat , but I see no way that can be true
dry and wet have different mouth feel .
on the other hand , dry meat has mouth feel similar to toughness , but was tender when moist.
extreme example : jerky
so rapid release will dry meat that's above the ' water line '
but the meat under the water line will stay moist and feel in the mouth tender .
one last thought : the dry parts of meat , above the waterline @ quick release , may ' chew ' tought
as is , but left in the liquid will re hydrate w time .
a tough piece of meat will remain tough in any liquid .
