Strictly speaking NAC becomes less required for copper detox as time goes on. The oxydized copper is usually up top where the Hg can get to it. After that you do still get some spots of it but mostly fresh copper which comes from cell repair and becomes the issue which is where MSM comes in.
Moly works for both but in particular for toxins like Tapeworm toxins bound to oxydized copper. Most won't need this due the doctrine commands but occasionally one gets a monster Tapeworm where this makes its way into the bloodstream. Itching is a main signal for this, 1.5-3k mcg are normal doses.
Now there is a new Sustained Release NAC that does work for both types of copper and is enough for most people. It is also acidified and can be taken with ALA\DMSA.
Another bonus of NAC in combo with the DNA Repair the cysteine left behind will aid your own GSH cycle to detox the body.