I am sorry, but not surprised, that this has been your experience.
Fosters are run by well-intentioned people with not a lot of knowledge or resources. I don't support any rescue or foster organizations for that, among other reasons.
I once attempted to adopt a dog through a foster organization. At the time, I was one of only a handful of internationally certified trainers using positive reinforcement based methods (and this certification took years and thousands of dollars to get but would let me work anywhere in the world), I owned a dog daycare and the dog could come to work with me all day, I had people also living at home so the dog would not be alone, I fed the highest quality food money could buy, I had big plans for this dog as far as training and performance sports. I also had three other dogs at home - two American Eskimos and an Australian Shepherd.
The foster organization declined my application because my fence in my yard was 5' and they require 6'. Seriously. For everything I could have given that dog, they declined me based on that.
I will never, ever (and have never since) support another foster or rescue organization. I've always been a purebred snob but felt a bit of a longing for this guy. I will stick to purchasing my dogs from purebred, registered, and ethical breeders who give their lives over to their dogs, and it's not just a volunteer gig a couple hours a week.
I know it's not much consolation, but you may have, in the long run, dodged a bullet wit these guys.