I don't know. But even if it's true, and even assuming we can develop a vaccine, how do you propose to go out and vaccinate every nine-banded armadillo, not missing even one population large enough to harbor the disease? This isn't an endangered species - they're all over the southeastern US.
You only need herd immunity. There is experience with vaccinating wild animal populations against rabies.
Well, okay, but I notice rabies is pretty ubiquitous. Rabid bats turn up where I live on a regular basis.
If it were a serious enough threat to the public health we could always exterminate the armadillo species. Make an animal legal to hunt, add a bounty, and the population will be decimated in under a decade.