Both of the "cute" responses to this post suggest a lack of culinary imagination. You are correct to ask this: no preservation method is taste-neutral, and moreover, this process requires a varietal that is likely quite different in flavour and texture to supermarket grapes, or even wine grapes.
I wonder if there are earthy notes picked up by the process? Similar to pu-er tea for example? Do the grapes become sweeter, or even partially fermented?