There are more than one type of rust. Cedar Apple Rust, Cedar Quince Rust, others? And strains vary by location and in virulence. Plus climatic conditions. So if you think CAR is an issue for you and aren't going to spray, a variety documented to be susceptible to rusts is a wildcard. If you really want to try it and don't plan to spray, go ahead and plant one or two and see. Just don't be prepared that it won't be a healthy, productive tree.
Goldrush should be immune to scab. That was the whole point of the PRI breeding program. Again, strains and climate matter. I have another PRI selection, Winecrisp, that looked to me to have scab this year (zone 6, PA). I can tell the difference between CAR, Frog Eye, Marssonina, and Scab so I'm pretty sure what I saw was scab. It's not good news if scab has mutated enough to defeat the genetic resistance introduced from the the PRI breeding program. Winecrisp and Goldrush have the same Vf gene for scab resistance. Other PRI selections may have other scab resistance genes.