I believe you tried.. I do not believe you recreated the scenario correctly.. I've tried it 3 times with me on top and on bottom.. the knees on either side of the ribs prevent the wrist from getting to the area above the back pocket.. the knees also prevent Z being able to hold TM's hand with is armpit.. the whole position prevents the reaching for the gun and the holding of the arm at the same time..
he's not saying/showing that he reached over the legs.. he's reaching between them and his body..reaching towards his back hip/waist area.. while holding TM's arm in his with his pit.
I wish I had a more accurate pic..
Here's Z showing how he did it.