Again, I'm not talking about the whole colony of GSP. I'm just speaking to the edge that is in contact with the other coral.
I took the time to comment in your thread because. Just thursday I took action on my GSP colony that was actually encroaching on my torch coral. In my case the torch was doing fairly well at keeping the GSP at bay. However, the GSP were getting the upper hand in my tank. Slowly but surely. However, that very edge where the GSP were getting touched by the torch coral, would never open. I'm talking about only 1 or 2 rows of polyps back from the edge. Yet, the mat kept growing and pushing towards the torch coral. In the end, my torch coral has no side effects from this happening over the last two or so months. In fact, it sprouted a new head right where the GSP were trying to take over. I placed a rock where my torch used to be, and placed the torch on top of the new rock. My plan is to put rubble at the base of the new rock and cut and remove the GSP as frags and replace the rubble for more to grow onto.