I have gotten chickens of all ages from a lot of different places and people and have never had a single problem with disease or anything. If they do then I will treat for it. It sure wouldn't stop me from getting chickens from someone else.
Chickenstock is my most favorite chicken activity, and our mini-stock at your house. So, I have to agree with you.I don't mean to diminish any biosecurity concerns. I also don't get too distressed over what may be a potential risk when it comes to expanding my flock.
My current group has come from at least 5 different sources over the last 2 years. Plus, other BYCers have brought birds here for swapping. My girls are hale and hearty and I haven't heard from anyone who has visited here that their flock has had any communicable bug. Even with the wild ducks that have grown up here, not to mention the wild birds that visit every day.
My sense of humour has me imagining a bunch of chickens in plastic bubbles, rolling around the yard.
And there may be a market for little chicken habitrails out there....