I would recommend, however, that you take biosecurity pretty seriously from here on out. Have boots and jacket that you only wear in the coop and thoroughly wash your hands after being around your birds. I would probably go as far as wearing fresh clean clothing when you head to the feed store. While its true that MG is not zoonotic to humans, wild birds and other people's flocks are at risk. So if you walk into the feed store with mucky boots and then someone else walks through there is definitely potential of infection of their flock.
In our case we are surrounded by 40 acres with no other domestic birds but many farms beyond that. I felt that the risk of a wild bird spreading it to other farms was unfair so we culled. I've heard many times that high percentages of birds have MG or mareks yet since I started drawing blood and sending in samples, I haven't had one test positive for either and my flock comes from four different sources. One being Beau Peep and they have birds from all over the place. It seems so irresponsible for a hatchery to knowingly perpetuate a disease that can be devastating to a flock. In some places MG among other poultry diseases is a controlled disease and your flock must be destroyed if they test positive as a means to control the spread. Yet a hatchery knowingly sells infected birds? I just don't get it.
K rant over hahaha! And really I agree with your decision, there's simply no point in culling with infected birds next door!
Hope your birds recover well from this outbreak!