You did well! I've been trying to think of a better approach, as I live downtown and there's a cart only a few blocks away, and finally, your experience is the one I want to have. As well as your outlook/attitude. It's admirable, and a fine example of an anti-witness.
To sum up I think I am pretty happy at the way I dealt with them and I felt it was on my terms and would encourage others to do the same ,not so much to say that they are wrong , but to find a common human ground to talk with them despite the way they respond ,for they are what we were and I can only wish they could find the wonderful freedom from the un-human behaviour of the GB and their power and teachings which change all the time.
Cheers!