Good point, Nick.
I was wrong too. :o The mass will counter changes in torque, but will do nothing for continuous application of power.
I can make this work. Add some paddles so there is drag acting on the mass. You could even vary the pitch of the paddles for yaw control. Hey, why not set up the paddles to create a bit of lift. Wait a minute....that's Kamov.
Seriously now, counter rotating fly wheels that balance continuous loads do exist. A mass-spring mechanism or the like that draw energy from the engines to supply the required centripetal acceleration to prevent the mass from flying off will accomodate a continuous application of power.
There are the same failure modes, weight problems, and control difficulties that I mentioned in my previous (sniff snifff...wrong) post, plus more complexity with the mass-spring or similar system.