Warmoth will not warranty the oil either. Only hard finishes. I have 3 guitars with unfinished necks, not a problem with them yet, and they went from Germany, to MD, to Korea, to Texas and now back in MD... so there have been a ton of climate changes on them. They are all maple.
Ah, and Van Halen plays unfinished necks too, if they can stand stage tours with Eddie, they will be good in my house.