User blog comment:Master Sima Yi/Assassinews 10-05'12 — World Gameplay Premiere/@comment-1888015-20120511183711/@comment-25419730-20120512095452

I'm guessing the guards backed away due to the fact that this is a trailer.

Just like that Brotherhood trailer that shows Ezio in Viana trying to stab Cesare with all his guards standing around, staring on.

Also, the fighting style is their choice. I don't think we've ever had a say in most things in the game.