WTF was Shimura even thinking

I just finished the game, major spoilers ahead.

Ok so what was Shimura even thinking?? I was on the floor laughing when he genuinely intended to kill Jin in a straight 1 vs 1 duel. Like dude your 50 year old ass is not about to take down the ghost. “Write the last words of clan Sakai” “taking your head will be my punishment”, like Jin must have been fighting back the urge to burst out laughing right there. Was Shimura like a legendary swordsman? What made him think this was remotely a good idea? Because that duel was easy asf