One of my teachers I think is quite expert regarding various types of shellac. She commented (when making general comments about shellac) that appropriate shellac applied appropriately would resist moisture (if not left too long), e.g., you could put a cold, sweating glass on a shellac coating for a reasonable time to consume the glass if you wiped the surface afterwards; however, she went on to comment that heat destroys any finish.
I would perhaps consider walnut oil with the notion that it brings out the grain and, although it perishes easily and quickly, it is just a wipe away from being restored. This doesn’t mean the oil will protect the wood from heat damage, though, and it isn’t something I’ve tried. If the user has walnut / nut allergies, you’d need a different oil. I don’t put linseed oil on anything, ever, so I cannot suggest that as an alternative. Not trying to kick up the linseed oil wars…sorry, but it was in context.