I've been safety-wiring over 40 years, 31+ years of that on a daily basis. But, I still make mistakes (rarely, but I make them). Cut it off and re-do it! No big deal!
I think that's the problem here - a big length of safety-wire between two bolts, obviously pulling one in the 'loosen' direction. Right on the front of the engine, plain as day, and yet the mechanic
didn't cut it off and re-do it. Was he apathetic or ignorant? If he can't get such a simple task right or be bothered to fix it when wrong, what else might be lurking, sight unseen?