Yes it does unscrew but can be difficult with needle nose pliers. Here is a link to Ausleys that shows the tool, If your bezel is in good shape it might be worth the investment
1964-68 Wiper Switch Nut Removal Tool
Ausley’s Chevelle has the world's largest selection of 1964-72 Chevelle restoration parts for sale including Malibu and El Camino. With 40+ years in business, we guarantee the best expertise, highest quality products and fastest shipping/service!