I had a mushroom farm in Northern Michigan some years ago and we grew Golden Oysters, among other species. I think our winters are too cold for them to really establish themselves, but I was hearing reports of them 'going native' in Southern Michigan as long ago as 15 years.
Like the farmer in the article, I also wondered about the apparent lack of effort in growing native species. My area has a wonderful native oyster Pleurotus populinus; exceptional in taste compared to other oysters, but I have never heard of anyone cultivating them.