You say your tanks have always had high nitrate, but this tank is new? You really shouldn't have high nitrate in a new tank. Eeep! Have you double checked your test kit?
I think the Gorgonian will be fine. Don't try to remove the sloughing except maybe with a turkey baster if you really can't help yourself.
It does look like it needs more flow though. That will also help with the sloughing, but by the amount that is still half tangled up on the Gorgonian suggests the Gorgonian doesn't have enough flow at the best of times. You can expect it to look this way for 2 days to 2 weeks before it will be done shedding, and the polyps will come out with a whole new zest. They usually look really good after shedding.