At this point, I think there are two questions (at least) that we need
to OP to answer.

1) Did the "wiring guy" hook up the equipment or just run wiring to
the locations where it was to go? And if he hooked up the equipment,
did this require opening it or did the owner just tell him to connect
cables that were already attached to the machines.

2) What were the agreed upon responsibilities of the "guy"? I assume
the owner hired him to save money, so he might be expected to do as
little as necessary to set things up, unless something more was agreed
upon. Asking what a licensed electrician would normally do might not
really be relevant...

Also, don't forget that in most places if the owner knew he hired an
unlicensed person, he (the owner) is probably liable for fines,
permits (possibly at doube the price) and at least having all this
work gone over by a real electrician if the authorities find out. If
it's anything like residential work, they might even force him to pay
a licensed electrician to rip it all out and redo it. I'd consider
that before raising a stink.