GF flour tends to soak up the liquids in whatever it is that you're making. The sour cream helped mitigate this from happening and added moisture to this yummy cake.
Important things to note when working with gluten free flour
I recommend sifting your flour. GF flour has a much different texture than regular all-purpose flour. This has a more crumbly and lumpy kind of texture.
Another helpful tip when working with gluten free flour
Note: the cake itself is not very sweet but it has just the right amount of sweetness when enjoying each bite with a bit of the persimmon and brown sugar topping.