People who say they want a natural appearance don't really want bare wood. There aren't many people who are willing to accept that their own dirt and body oils will be the final finish on a pen. Pens that are finished that way look like what they are - dirty wood.
That natural feeling of the wood people say they want is more a visual thing than it is how the wood feels in their hand. Our eye sees glossy and it tell our brain that it feels like a hard finish, and it does, even if it is highly polished bare wood. Our eye sees a matte finish and tells our brain that it will feel as soft as natural wood, and it does, even when it has a finish coating on it.
My advice would be to put on a CA finish. Sand it to 400-grit. Then use 0000-steel wool in both directions.
Make a pen this way and ask if this is what he wants. He will think that the soft gloss is natural wood, and you will know he won't be coming back in a month with a complaint about the wood getting rough and ugly from handling. Both of you will be happy.
Do the same thing with the stabilized wood.