Sundhedsdatanettet actually runs on "public IPs". They aren't public, they aren't routed and they certainly are not connected to the internet, but they do exist within a public range. Not sure why a private range wasn't picked, but I'd guess it's to avoid conflicts with other networks.
Could that actually provide a benefit, in that if someone accidentally DOES connect it to the public internet, all sorts of things break immediately and obviously?
If the two networks are entirely separate, and they absolutely must be, then there's no reason for addressing concerns of one to influence the other one iota. (Except that certain OSes might have baked-in assumptions about things like the 127/8 network, so you'd have to work around those.)
Sjunet also uses public IP, but never exposes those on the Internet. No clue why, probably it turned out to be the easiest solution to avoiding collision with private ranges used at all member organizations.
