Hmm, I don't really follow this scenario... why use Nutanix as a backup target?
Supposedly, Nutanix is designed to run your production VMs. I was under impression that it is very expensive, so probably it is an overkill to use one as a backup target?
This also adds additional level of unneeded complexity between you and your backups - and an extra technology to deal with, something else that can brake or start misbehaving. Follow the Occam's razor principle
Finally, your backups are no longer easy to get to, as they are inside VM, inside Nutanix. Compare that with storing backups on a SAN LUN or a file share, that can be easily reconnected to any physical computer for emergency backup retrieval (even to your laptop!) should all your servers die.
Are you sure this is a good idea? Perhaps you could share some of your thoughts around that.