Most(wise) people deal with it in the same way you did. Let em shout as much as they want. Sticks and stones may break my bones...
Kudos for keeping cool and doing what's right. But your post heading ain't right. It's assuming and generalizing as
a)You are not sure the abusive driver in question was Qatari
b)even if he was, not all Qataris behave in this manner.