I remembered that I can disconnect the virtual Ethernet cable on the virtual machine. So I did that and tried opening TurboTax again. It then presented a new dialog telling me that "To get software updates, you need to connect to the Internet," with buttons that say "OK, I Am Connected" and "Cancel". Clicking Cancel takes me to the previous dialog that shows with the virtual Ethernet cable connected. So instead of closing that dialog (which terminates TurboTax completely) I chose "Continue Updating TurboTax".
Unfortunately the updater had already downloaded the available updates. It went ahead and applied the California State form update, but the Program Update requires elevated privileges. I canceled that UAC dialog when it appeared, TurboTax put up a failure dialog, and I was finally able to get into the program and change the Update Preferences back to "Ask me before getting updates".
"Spaghetti code" 🍝
