He's a several year old corpse, moisture tends to do terrible things to such. He undoubtedly has pymarics to keep his body dry, like he does for his tongue, eyes, and lungs. I can see how a water woman would interpret a touch that destroys any water in contact with him to be 'burning', at least for skin-to-skin contact.
My heart breaks for Duane, when even creatures as old as time look upon him and declare him ugly.