No...not surprised. Been baking with buttermilk and know it contributes to richness and layers of flavour. Then again, never tried it in omelettes. I like making them, but they don't like my digestive system...
I have made pancakes with milk and other recipes with buttermilk. Buttermilk by far is so much better. One question I have? I have used the powdered buttermilk where you add water. . .. this may be a dumb question, but is there a big difference with using that versus something that is not powdered?
According to Harold McGee (under scrambled eggs), milk/water/even oil added to eggs dilutes the protein and results in a tenderer product. I usually throw a bit of milk in mine, but the buttermilk idea is intriguing and I'll have to give it a try.
I use what ever is available. Adding sour cream, yogurt, hvy cream, even herbed cream cheese thinned with water, they all add a tenderness to the scambled eggs or omelet, each adds a distinct layer to the taste. The more acidic the addition (sour cream, yogurt) the more tender.
12 yr old grandson considers the scramble with yogurt a gourmet item that only his grandma has to secret to. Oh, the power, the satisfaction of being so perfect in his eyes!