Inspector
Nyuck, Nyuck, Nyuck!
One thing you could try if there is a next time is to soak the soft areas with thin Cyano Acrylate glue. It will penetrate and harden the wood if you work through it sanding soak it some more. Don’t let it get on areas that are sound as it will not allow a finish to penetrate like the unglued area does. Some of the wood hardeners used for house repair might work to.