Well, I don't know whether or not that is true. It's possible that the British government considers him to be a British citizen. I'll let the legal experts worry about that. So long as he never acted on it, and never obtained a British passport or never partook of any of the benefits of British citizenship, I don't see why anyone should care.
I'd rather focus on attacking him for real unpatriotic acts that actually matter, such as his decision to give war criminals captured on the battlefield access to our civilian courts.
Yep, that is very nice progressive "Tap-Dancing"!!!