Grayhound owner is doing the correct thing.
I had a dog that was a rescue and really mean. Was out hiking and of course he was on a leash. I was hiking around a group of people I didnt know) and just let them know not to pet him - they were fine with my dog.
Problem came up when a lady came hiking onto the rocks (we were climbing across a "ledge") with her dog off the leash - the other people told her to leash the dog cause they didnt want it loose, she didnt and her dog went to say hi to my dog, I yelled to the lady to call the dog back - she didnt , just looked at me with that "whatever" look.
My dog and I were on the ledge and when the dog got close, my dog went to protect me - almost ended up pushing me off the rock to get to the other dog - I was able to get my dog to stay for a minute. Thats when I punched the ladys dog on top of its head - the dog took off, (he wasnt a mean dog but my dog would have tore him up) the lady was going to bitch about me hitting her dog but the other people told her to leave the area..... she did, with her dog still off the leash!.
Anyways, the Grayhound owner did the right thing. You also did the right thing to warn the other dog owners, you didnt have to do that but it was great you did -
* This was my dog Cody, that passed away last year, not Hudson - he would never hurt someone on purpose.