Putting a finish on ash splint

I have read various opinions at several sites regarding putting a "finish" on ash splint seating. Everything from "don't do it," to shellac, spar varnish, to wipe-on poly, etc.

I am working on a Old Hickory style barrel back seatee swing that is on a boat dock during the season. The current splint is "white" due to sun bleaching. and broken through. Don't want to seal the splint so much that it becomes brittle but also want to provide some protection.

Any thoughts and suggestions are welcome.

Thank You! George Collins