Shad, emeralds are typically reef safe. Apparently there has been a rash of emeralds recently that have taken to munching on some softies. Previously this was not the case. However, they are animals and nobody can vouch for certain how they'll act in a captive environment.
My suggestion would be to move them to your fuge at this time. I wouldn't want to see them continue their munching on anything else.
I added a frag of xenia to my tank and my emerald crab tore it off the rock and ate it. it doesn't bother my LPS tho. and I found another emerald in my tank a week later. You can always put him in a betta breeding container with some liverock and hang it in your tank.