This is very simple. Snow on the wing is BAD & WRONG. Dry snow, wet snow it doesn't matter what type of snow, its wrong. Whats under the snow? You cant know whats under the snow until you have carried out a tactile check and I do not believe that this IB crew, or any other A340 crew is likely to carry out a tactile check extent necessary to determine weather or not there is ice under the snow. Different parts of the wing will be at different temps and so what is under the snow will vary across the wing.
Will the snow blow off? Maybe it will, maybe it won’t. You don’t know and neither do I.