I agree. The theory can be rubbished in very simple terms: The inventors assume no new physics, and conclude their device will violate conservation of momentum. All the 'input' physics conserves momentum. Therefore their analysis is wrong.
If I give you a list of numbers which are all even and ask you to add them up, and you give me a sum which is odd, I know you've messed up. I don't need to check the details of your adding and point to exactly where you went wrong. This situation is analogous.
So if the device *does* work (which I very much doubt) it will be pure wild coincidence, not due to any cleverness on the part of the inventors.
(Note: these comments are based on the description of the EmDrive in New Scientist some years ago. I am unfamiliar with the Cannae Drive, so I don't know if it has the same theoretical flaw. If it *does* end up working, I will revoke my vow to never again subscribe to New Scientist.)