The mold is harmless so it can be wiped off or left on. Most of us do see mold as a sign of spoilage but not in this case. If the mold is any color other than white or off-white/cream it will get wiped off with a vinegar solution. The good mold serves a couple of purposes. First off, it protects the meat from yeasts, molds, and bacteria that occur naturally that could spoil the sausage. It also helps to prevent the outside of the sausage from drying out and hardening which trap moisture and not allow the sausage to dry properly.
For long term curing you should use Cure #2.
Do you know if your grandpa dredged them in salt long before hanging them?
I was pretty young at the time, so I really don't remember about the sausage. I know he used Morton's Sugar Cure for the hams...no smoke. I know he used brown sugar mixed with the salt.
For the sausage, covering with salt prior to hanging and drying, sounds like a good idea to keep it from spoiling.
The guy I've been buying air dried link from the last few years, never has it ready till sometime in January. I'm assuming that's because he's waiting for good cold weather before hanging. Around here, we really only have a short window to hang meats outside without temperature controlled environment.
I'm thinking about asking the guy I buy from now, if he'd share his secrets before their lost, like with my Grandpa. I wish I'd taken more time to learn more from him when he was living. He only went to about the 6th grade in school but he could do math in his head like a calculator! He was a farmer and building contractor. He built some really big houses in a local gated community. You'd never know from looking at him, how much he really knew.
We went out in the woods once and cut down a small White Oak tree. He showed me how to split it into strips and then we used it to cane a chair bottom. I really enjoyed documenting that, wish I'd learned more....dumb kids!