I would think that a finish would be a necessary precaution. Right now the humidity feels like 100% and in the winter we get down to maybe -10 F. I use nothing but Fatback necks and they all have finishes. The winter conditions mandate that we use the heater so I also run a humdifier, not because of my guitars although they benifit, but because of my asthma. Now if they just invented a finish that would protect my guitar from tornados I'd be in business.

Tung Oil sounds like it would feel great and if youre willing to take the 0.1-10% risk than I wouldnt hesitate.