First of all, rosewood is a very dense and oily wood. There's dense wood like ebony that's lasted for 4,000 years in tombs in Egypt. So I wouldn't worry.
PRS recommends simply an occasional cleaning with a lemon oil product like their fretboard conditioner, and then sealing it with ordinary Behold furniture polish. When I had RW neck PRSes this was necessary only 2-3 times a year.
If your hands are very sweaty, they can raise a little "fur" on the unfinished wood. This is very easily dealt with, by gently rubbing the neck with a micro-mesh sanding cloth in the very finest grit for maybe one or two gentle swipes, and then do what you'd do with the fretboard conditioner and polish.
The PTC also has a special rosewood treatment that is called something like "Treatment of Awesomeness" (I can't actually remember the name), and it's supposed to make the necks feel like glass.
The rosewood neck on a PRS will outlive YOU, your children, your grandchildren, your great-grandchildren, and your great, great grandchildren at the very least (unless you do something really foolish with it, like leave it out in the rain for a week, or put it in the bathtub). There are unfinished rosewood fingerboards and of course the insides of rosewood bodied acoustic guitars are unfinished, that have lasted for hundreds of years.
So when your great, great-grandchildren are playing electronic accordions that they can control only with thought waves, and wondering WTF you ever saw in a guitar, that rosewood neck will still be in great shape and functional.
However, it will be in a museum. Hard to say where you will be.
