Had you not given Z such good training, it might have ended differently. Good job! Nice that the owner of the two dogs realized the error and apologized. Sometimes dog owners get overly defensive, even if they're in the wrong.
Way to go, Z! And goldendog.
I ascertain from both of all your posts that Z is on a fairly regimented schedule of walks and training. So hard to be consistent, but you two are very good at it. And I suspect it is doing Z well.