Just drag and drop the Twiddler disk to the trash can as you would any other USB drive to unmount it.
Remember the Twiddler3 presents itself to the OS as a 2MB USB storage device. The OS sees that and automatically mounts it. If you are not writing to it, forcefully ejecting it should not be an issue.
Also, why not use Bluetooth? It solves the problem as the USB drive only mounts via USB connection.