Is this a home inspector hired by the buyer or seller, or was he sent
by the bank?

I don't have my NEC book with me and I don't know the tchnical answer
to your question, but around here, it would be unusual to have a main
breaker inside the house. It is usually in a box attached to the
outside of the house. If it's easily accessable from the property,
from gound level, I fail to see why being away from the house is a bad
thing... (Bu, that doesn't mean it isn't against code.)