I think the bottom line here is that, if for some reason a fire did happen and an investigation of the cause of the fire came back to that wiring, then insurance may not cover the damage the fire caused.
Same for if someone got shocked and hurt or killed from that wiring plus he could be liable as well.
If he feels confident nothing will ever happen, then he can take that risk and do what he is doing.
It's always best to do wiring to code. It's not that hard and it's not that expensive.