[quote=HollywoodMole]
I looked at the argument, even though one guy left, it's pretty obvious he was being over aggressive as hell.
[/quote]

This.

Based off what I saw, the above is definitely true - all things considering, Narrator chose a fairly common combination, and went a little over the top in pointing out that someone else did it, including leaving because of it.

In that situation, everyone could have handled it better, GM and players included. Probably could have talked to both of them, as Sword and Magic is common and no reason to quit an RP because someone else chooses it.

As GM, it was likely bad form(and left a bad impression on Experta) that you essentially told him, you weren't going to lose another player in that fashion.