+1They didn't leave a 40 amp breaker to be installed - they left a 60 amp breaker. The pullout is not fused, it's just a sliding switch. If it made a snapping noise it would just as well be a big snap switch. Speaking of which, that's what they used on the furnace for a disconnect: a regular ol' light switch.
You will not get any argument from me that what they left him is compliant.
Almost all of this discussion had been about what different scenarios close to what they left might be compliant. And all of them involve work to be done by an electrician.