No it isn't that simple, because a 1BTC on a MTGox account isn't the same thing as 1BTC on the blockchain, if it were then Gox wouldn't have collapsed the way it did.
MtGox internals don't matter for tracing the lost coins. You need to know all addresses owned by MtGox, then you also know all the coins deposited to MtGox, and you need the list of legitimate withdraws. Then you can just look what happened to the coins not legitimately withdrawn.
