I tired with 4 versions on TB and couldn't get that result.
Also if you watch Kordiss's replys, youll see that in the first one he extends his elbows, while in the second one they are just on hold.

Magix got that. Its really weird.

Well maybe it's the matter of FPS. Like if you have a small FPS, and you get a dismember on the last frame, you don't see it unless you shift+p through the replay.

Because i did exactly the same movement on both tries and the results were different. Just like kordiss said. Without extending elbows.

I've done it for the same way as you did, and it is bugged for me too xD

That's stupid

funny... it happens

Im going for a wild guess here
toribash analizes if 2 objects are colliding every x frames and on every turn
x>1
so when the tf = 1 the collide anasys happens every 1 frame and the hand doesnt go inside the joint (that helps dismember it) and there is your "glitch" (that it really isnt)