As an up and coming pen maker, and avid woodworker, I am very interested in this issue.
When I drill the hole for my straight holders, I insert a brass tube with sufficient epoxy to completely seal any open wood. However, I have not done this with my obliques. I use a Zanerian style flange, so the slot is not sealed when the flange is installed. I wonder if it might be worth the effort to drizzle a small amount of CA in the slot, then recut it when its hard. Sort of a simple stabilizing technique.
It may only be an issue with certain woods. Some woods, including many from the tropical climes, are very rot resistant. While others can be affected very quickly. A few North American timbers such as maple, can sucumbe to this if left in damp contact. This spalting (rotting) effect can have some beautiful results, however once it has started, it must be dried and sealed, or it will quickly continue.
Woodworking is a hobby in which you never stop learning. I am looking forward to here the results of tis investigation.