A valid concern. I'll look around the garage and see if I have any of the crushed walnut to do a weight comparison.i would be concerned.....more about durability of the vib machine.
fluid is a lot heavier than media, and adds more stress on the bowl from the weight and handling of the bowl.
but it seems to work. I am thinking it will accelerate wear on the device due to the additional weight of a now liquid media being substituted for dry media.