It will be ok, but my tank has been set up for over 3 years, and I had beautiful live rock that came with the cutest little urchin the size of a pencil eraser. Well, that baby grew into a tennis ball almost and ate every bit of coralline off my rocks. Well, it past away a few months ago and my coralline is starting to come back, but nothing like it was yet.
All they are saying is if you want bare rock, get the urchin. If you want purple coralline, dont get the urchin.