Hmm...how to describe this in english.
1st- Piece is not fixed, if hes not holding it, can easy slide to back side of blade and will be projectiled directly in head,torso...
2nd- That triangular piece can be pulled first in the blade and when its pulled in hole , saw bends wich will make less space for handle piece wich man is working on. That will result in compresion of it and will be thrown or diagonaled wich can lead to ugly cut on left arm, i asume man is holding it with it. Right one is on jig.
3nd- Since his jig is on right side man stands directly behind blade.
And im sure that there is more
Why better or left side:
1st - Your body and head are not aligned with saw
2nd - If triangulate piece is pulled inn the hole betwen saw and table you are away and you have more control over working piece, since you hold it with right hand you will push it left away from blade and not in it.
3rd - You dont need to cut all the way true the handle and you can easy remove triangular piece when 2-3mm still holding on end. You can free one hand for that, easy. On right side that is not possible sice left arm is holding working piece and right one is holding jig.
4th - You cant cut yourself so easy as on right side
5th - All maschines have jigs for diagonal cuts on left side.
Important! There is protection missing behid saw.
Sorry for my bad english. I hope it can be understood.