I was recently a victim of a grief in my town and the portal sign was destroyed rendering it useless.
I believe there should be a warning on the ECC Wiki or elsewhere to let players know to check/lock the signs when the portals are put in. I couldn't find anywhere that mentions that it needed to be locked. I was under the assumption that since only Wewinagain could put them in that he was the only one that could break them. Apparently this isn't always the case.