[Aerkuld]

I work with a guy that I suspect would rather win the goat, but that's another matter...

I don't think the probability changes through the whole scenario as it is described.
When the guy makes his first choice there is a 100% chance that one of the other doors will reveal a goat. This leaves him with the same probability when one goat is revealed as when the initial selection was made, hence changing or not changing his choice at this point will not change his odds.
As for the host knowing which door hides what it is irrelevant in this instance as we know the outcome. The only difference it would make in the game is if the host didn't know and opened a door to reveal a car, but we know that is not the case.