You're not actually doing it a favor by disuse, the pane gasket is an air-stop but isn't meant to stop water. The drains do that. The biggest favor you can do a sunroof is don't park under trees. The most pernicious drain clogs are always tree sap mixed with dirt.
Easy to tell from the VIN, first character J=Japan, K=Korea, 1 or 5=USA (I think US Rogues are all 5).
Btw, I only ever saw a disconnected drain once before on a new Nissan, but it was also a Rogue (gen2). The drain wasn't actually disconnected, it was missing.
We see half the sunroof problems in Arkansas and I have yet to see one on a gen3, but there's still nothing mysterious about sunroof drains. If they can't fix it then I have no idea why. I'd also love to know who the "engineer" was, DTS's aren't usually engineers (with one exception that I know of) and don't pretend to be. Something here smells fishy.