Do you mean compacts in general or the '87-'91 ones coated with the smooth thin shiny metallic layer (I am want to call it "paint")? Have you read further reports of retrobright harming the original '84-'87, and post '91 matte-gray paint?
From my experience, no one has reported ANY damage from submersion to the matte gray, rough-textured, thick paint coating used on the original 128K through early Plus, some SEs, and again later on the Classics. The only reports I have seen have been from the 1987-1991 SE, Mac Plus, SE/30s and some Classics with the shiny metallic coating.
Also, for what it is worth, no one has ever reported that submersion has damaged ANY paper or plastic labels. In fact I would be somewhat concerned that partially covering one of the plasticized/vinyl agency labels on the back might result in splotchy discoloration, since these labels have been known to yellow as well.