I can see that there are several things taking place in the picture which beg for an accident to happen but I don't consider leading the horse from the off side as one of them.  I can't remember the number of times I have had to point out to novice horse people that all horses should be equally handled, led, mounted, & bridled both on and off side.  You must anticipate all problems including those in which the sole solution will have you lead or mount on the off side.  I got thrown when I was 15 and broke my left leg in a few places.  I was in a 49 acre pasture and well out of earshot for any help.  My only way out was on my mares back.  If she hadn't always been handled from both sides, and become accostomed to it, I probably would have had difficulty in mounting her on the wrong side. Thankfully, I did not and in a few minutes we were back at the barn and an ambulance took me to the hospital for the first of 3 surgeries to repair my leg.  At the end of the day it needs to be common sense that guides our safe horse handling.

Kindest Regards,

Theresa