You've got me thinking Brian. Now that I have the new prop hub I have some time to rework the old one to become a usable spare. I could accelerate the corrosion if I used mild corrosive solution. I could drip some into the hole and let it sit in my basement, and add a drop or two each day until the embedded tap disintegrates.

This table http://www.engineeringtoolbox.com/metal-corrosion-resistance-d_491.html shows bronze is resistant to boric acid, milk, whiskey and wine -- but carbon steel is not.