This is just a kirf dutch. Precision falling with minimal splitability, AND butt pounding ground action,(so you dont loose any wood..
Your 3rd gen buddie probably did it to ensure as good as possible the butt from jumpin off the stump during the leveling.
A kirf dutch without a snipe is not really dangerous but may allow the tube to acomplish some nonsence sutch as severing one side of the hinge and ... Tree did not go where it was supposed to go..
A kirf dutch or box cut is great for keeping fibers glued. Next time you guys get a small heay leaner, make a first face cut about 1 inch and back cut leaving healthy hinge and see what happens..
Fall, fall, fall, commit to the face(snipe) and POP, doup,(butts on the deck) and POOFFF... She's LAID!!
Just my 2 scence.