That guy is a moron. even if it was over filled, why would fixing it be any different than doing a regular oil change.
I guess opening the drain plug, and the oil cover on top.. that would be 2 things that need to be opened.
And how over filled was it? It can't be too bad unless you put like 6 quarts in..
(disclaimer: I'm no expert, so don't shoot me if I am wrong, just using logic)